Evinrude Outboard Compression ChartPull all the plugs and test the compression, throttle should be open while cranking the motor, all should be within 10 percent of each other. Evinrude Outboards : Compression. Engine Repair and Maintenance Johnson & Evinrude Outboards Compression on a 1975 Evinrude 70 hp iboats625 Aug 28, 2013 iboats625 Cadet Joined Mar 18, 2013 Messages 12 Aug 28, 2013 #1 I have a 1975 Evinrude 70 hp. Yeah, that is pretty low for a 4hp, these engines have higher compression than the older 3hps. See the model number code here. We have 2 Evinrude E-TEC 250 manuals available for free PDF download: Service Manual, Original Instructions Manual Evinrude E-TEC 250 Service Manual (416 pages) Brand: Evinrude | Category: Outboard Motor | Size: 36. Plus, the outboard motor or your boat goes through a constant combustion cycle. Whatever the engine type, you have the entire technical specifications for a better choice. Everything You Need To Know About Outboard Compression Tests. Evinrude Portables Full Specs: Portable Outboards. The calibration of the gauge was verified within a couple of weeks before the reading was taken. Often times head gaskets are replaced when removing the cylinder head to check on the status of pistons and the cylinder walls. If one or more cylinders are damaged due to improper timing settings, lean fuel condition, overheating, or stuck rings from carbon buildup, your outboard is about to become history. 310 Apr 20, 2010 #1 Ok, I started a thread a little bit ago about my 1965 johnson 9. However if you watch the end my video below you will see that my 1979 Evinrude. Everybody hears about performing an outboard motor compression test, and everyone knows that when you buy a used boat, you should compression test the outboa. Now the Four-Strokes have more moving parts. We have 2 Evinrude E-TEC 250 manuals available for free PDF download: Service Manual, Original Instructions Manual Evinrude E-TEC 250 Service Manual (416 pages) Brand: Evinrude | Category: Outboard Motor | Size: 36. I have provided a one-stop-shop regarding where to find the replacement parts for your old Johnnyrude outboard along with instructions on how to perform yearly maintenance on your motor. 2 Cubic Inches with a Wide Open Throttle of 4500 RPMs. Using proper grade of gasoline and outboard oil is essential to preventing internal problems. How to do a compression test on an outboard motor. However, four cycle engine cylinder compression should still be within 10% cylinder-to-cylinder. The clogging of piston rings with carbon is another common cause of a low compression reading in your engine. Apr 11, 2009 R Redmen Cadet Joined Sep 18, 2008 Messages 7 Apr 11, 2009 #1 I Have A 1997 25hp Evinrude, 3 Cylinder, Electric Start, Oil Injected Outboard. I just checked the compression on all 3 cylinders and it is 150# on each. Some outboard designs will read well into the mid hundreds. I didn't have a lot of time to troubleshoot it last night, but did do a compression check and the numbers have me a little puzzled. After the engine has run and is at normal operating temperature, insert the compression tester into the spark plug hole in any of the cylinders. rearward out of it's hole. So whether your are rebuilding / resealing your lower unit, rebuilding your carburetor, or replacing your thermostat or water pump you’ve found the right place!. Chrysler Outboard Compression. Johnson Evinrude Outboard Motor Parts by Year 1955 to 2011. A Johnson outboard compression chart is a graph that shows the amount of compression in the engine of a Johnson outboard motor. 1988 Evinrude 225 HP E225TXCC This 225 horsepower Evinrude outboard, manufactured in 1988, is a saltwater model. You may ignore any letters before the horsepower designation, and those after any of the following model numbers that match yours (e. Outboard Motor; E-TEC 250; Evinrude E-TEC 250 Manuals Icon Remote Control System Troubleshooting Chart. 5 HP 1964‑73 10 HP 1958‑63 10‑14 HP Commercial 1982‑94 Pin. Pre-1980: Evinrude outboards prior to 1980. Four cycle outboard motors produce much higher compression than two cycles. This 25 horsepower Evinrude outboard, manufactured in 1978, is a saltwater model. Johnson Evinrude Model Numbers: '110MLCD'. The type and model is what matters in an outboard’s compression readings. Johnson Evinrude Outboard Motor Service Manuals PDF Download. Outboard Motors & Engines, Parts and Accessories | Evinrude US | Evinrude US. If there is a need to buy a reliable, economical and powerful outboard motor, Evinrude power units will be the optimal solution to this problem. the motor set up for a while and they ran it last summer after a loooong period of sitting up. Compression is the heart of an outboard. Knowing how to perform a compression test is essential if you are buying or maintaining any outboard motor. His rings are shot/ worn or well down the road, skimming the head will do nothing as thats not the prob is it? And niether is there such a thing as "mechanic in a bottle". The late 80’s 200 hp looper motors only had about 85-95 lbs when new. Re: 1985 Evinrude 90 HP Compression readings? On most Johnson/Evinrudes you want compression numbers that are within 10% of each other and preferably over 100lbs. The clogging of piston rings with carbon is another common cause of a low compression reading in your engine. 1980-Present: Evinrude outboards from 1980 to the present use a model number that can help determine the year and features of the motor. As we continue to support our. I am looking at a boat with a 1988 evinrude, I asked about the compression and here are the results I was given: starboard block upper-115, lower-120 port block upper -108, lower108 and new water pump, intake strainer and plugs done a well. The test measures how much pressure is built up by the motion of the piston inside the. Understanding Johnson Outboard Compression Chart. Knowing how to perform a compression test is essential if you are buying or maintaining any outboard motor. Compression in a 2 stroke outboard?. Shaft Length - in (mm) 20 (508) | 25 (635) Engine Type. 70 HP Johnson compression test. Is this reasonable ? faztbullet Silver Medal Contributor Feb 25, 2015 #2 No L leaky. First, stone cold and came up with this: 1 - 81 2 - 81 3 - 88 4 - 86 Then got it to run for about 3 minutes with cuffs (having some fuel issues, I believe) and got this: 1 - 80 2 - 80 3 - 90 4 - 88. Service Manual 5007213_Evinrude E. Your Johnson Evinrude model number is the key to finding the correct parts for your outboard motor. EVINRUDE ® E-TEC® G2® INSTALLATION COLOR SHAFT LENGTH - in. 79 MB Table of Contents S M Ervice Anual 4 Table of Contents 4 Safety Notice 6 Abbreviations Used in this Manual 8. Those heads ran compression around 90+. To perform a leak down test, you would pressurize the cylinder with compressed air. Find the full specs for the Evinrude Portables. 1985 Evinrude 90 HP Compression readings?. Evinrude E-TEC OUTBOARD WILL NOT START OUTBOARD HARD TO START OUTBOARD WILL NOT SHUT OFF OUTBOARD STARTS AND STALLS OUTBOARD STARTS, LOW MAXIMUM RPM EXCESSIVE SMOKING OUTBOARD SURGES, RUNS ROUGH MWS Instrument Wiring Harness Lanyard Switch / Emergency Stop Circuits MWS Key Switch and Nuetral Safety Switch CANbus Keyswitch/TNT Wiring Harness. Boat Manufacturers - Listed Alphabetically Boat Manufacturers - Listed by Boat Type Outboard Engine Manufacturers Boat Part Manufacturers. This compression is. Buying a used Outboard? What is Good Cylinder Compression? 6 Hp or 9. What is good compression for a 9. RPM Information: 5000 Your engine's RPM range is important in choosing the right propeller for a given application. The displacement for the pistons is 183. 225 HP 200 HP 175 HP 150 HP 115 HP 90 HP 70 HP 50 HP 40 HP 25 HP 15 HP 9. Due to the presence of the E-Tec direct. New and vintage parts available at MarineEngine. 60 (92 x 66) Displacement - cu in (L) 158. I had taken the previous owner's word that the. Any rate below 90 is considered a low compression. Net dedicated battery charging power output is 50 Amp. Apr 10, 2017 #3 RitcheyRch Currently Boat-Less Joined Sep 20, 2007 Messages 62,305 Reaction score 70,094 Thanks for the information. your 6 HP model # BJ6R4SOSM would match 6R4SOS in the chart, ignoring the " BJ " and " M ") 40 HP. Make sure that the plug leads are well clear of the flywheel or any moving parts. EVINRUDE/JOHNSON OUTBOARD APPLICATION CHARTS 9. I have provided a one-stop-shop regarding where to find the replacement parts for your old Johnnyrude outboard along with instructions on how to perform yearly maintenance on your motor. This outboard engine weighs approximately 288 pounds. I have a 1989 15hp Evinrude, same powerhead as 9. Compression is about 125 psi on each. Only trouble is getting the wiring harness to fit as the new motor is VRO and has a few more censors and the old one does not. evinrude/johnson never had a figure for the compressions on the engines from the factory, all they state is that as long as they are within 10% they are ok. says: Baloney!! Mastertech! MODEL YEAR CHART 1970 - 1979. After the engine has run and is at normal operating temperature, insert the compression tester into the spark plug hole in any of the cylinders. Make sure the fitting screws in correctly and avoid cross threading the fitting. What Outboard Compression TEST RESULTS Tell You! Born Again Boating 85K views 2 years ago How to do a compression test on small engines. Metal In Motion Shop 66K views 2 years ago Tohatsu 20. Evinrude Outboard Motor Model Numbers & Codes. Is the too good or are they too high?. The model number will also help determine the "model year" of your motor. Evinrude Parts & Johnson Outboard Parts at MarineEngine. The engine weight is recorded at 455 lbs. Evinrude outboard engines are lightweight and feature quiet operation. do an Outboard Compression Test. The model number will also help. Engine: 1978 Evinrude 25 HP (25802). You may have to modify a wrench by thinning it as there is minimal room. Knowing how to perform a compression test is essential if you are buying or maintaining any outboard motor. An Evinrude outboard designed for every type of boat application. One gauge will tell you the pressure of the air compressing the cylinder. MODEL YEAR CHART FOR JOHNSON OUTBOARDS 1970. Conclusions Older two cycle outboards, especially low horsepower, can run fine around 60 psi however above 90 psi is optimal. Yamaha Outboard Compression Evinrude Outboard Discussions 4-Stroke Bracket Cable Carburetor Code Color Compression Condensor Cooling Cover Crankshaft Cylinder Dealer Diagram Drive Electric Engine E-TEC Exhaust Ficht Flywheel Fuel Fuel Pump Gasket Gauge Gearcase Identification Impeller Key Keyswitch Leak Loss Lower Unit Marine Model Number New Oil. The bore for this outboard is 3. Outboard turns over: Low or no compression: Check compression: Outboard turns over: Water in engine: Check condition of spark plugs and cylinders: Outboard turns over: Internal powerhead damage: Check and repair as needed: Outboard turns over: Leaking cylinder/crankcase, intake manifold, or reed valves: Check and repair as needed: Outboard. Outboard Motor; E-TEC 250; Evinrude E-TEC 250 Manuals Icon Remote Control System Troubleshooting Chart. Take a compression gauge and thread the fitting into the number 1 spark plug. The bore for this outboard is 3. Shaft Length - in (mm) 20 (508). flyingscott Fleet Admiral Joined Apr 8, 2014 Messages. 1994 Johnson 225 hp outboard motor compression test. When you are ready to begin the test, hold the throttle wide open. 41 (351) Gear Ratio (shaft length) 2. 2005 250 HP 225 HP 200 HP 175 HP 150 HP 135 HP 115 HP 90 HP 75 HP 60 HP 50 HP 40 HP 2004. As far as I have ever known (some may disagree, but I have always followed) once you get below 100 psi your getting border line on whether or not the motor is gonna run much longer. Knowing how to perform a compression test is essential if you are buying or maintaining any outboard motor. Cylinder compression test of a low hour Johnson Evinrude 25 Hp Outboard Boat Motor An outboard has good compression if the values are above (roughly) 70 psi and are EV. I have a 1989 15hp Evinrude, same powerhead as 9. The displacement for the pistons is 31. The highest difference of the readings should be 10PSI of each other. 6) Full Throttle RPM Range 5400-6000 RPM Starting Electric Controls Mechanical Fuel Induction E-TEC Direct Injection with. This realy is rubbish as if all 6 cylinders showed 60 the engine would be useless, but i would expect atleast 115 maybe upto 150 on all 6 pots. Ended up getting a Evinrude 70 parts motor with good compression. Evinrude 25hp Compression. Apr 11, 2017 #10 RitcheyRch Currently Boat-Less Joined Sep 20, 2007 Messages 60,210 Reaction score 60,450 Thaks and will keep that in mind. Some smaller rope start motors will only give readings of around 80psi, but as long as the reading are even across the cylinders they run well. Cylinder compression test of a low hour Johnson Evinrude 25 Hp Outboard Boat MotorAn outboard has good compression if the values are above (roughly) 70 psi a. MODEL YEAR CHART FOR JOHNSON OUTBOARDS 1970-1979 Wondering "Where-'n-'Ell" to get great parts for your outboard? Right Here! A Fun Old Porcelain Sign and Ancient Tools Meet the MasterTech! (click picture) If your Mfgr. Sometimes having compression as low as 80 and 90, the engine will still run great! We'll talk about low results in a minute. You might try a different compression gage, readings can be inaccurate on these small combustion chambers. Model numbers are usually found on an ID tag on the mounting bracket. Low Compression in One Cylinder Outboard: Cause and Fix">Low Compression in One Cylinder Outboard: Cause and Fix. They don't have ports like on the Two-Strokes. Try a second gauge to verify the readings. 5 Hp Johnson Evinrude Lower Unit Not Shifting into Gear; 9. It's just missing a few parts so im in the process of swaping out parts. Plus, the outboard motor or your boat goes through a constant combustion cycle. To find the one that's right for you. I hope this answers your question. 15 hp Johnson Compression. This model has a electric starter and power steering. Shortly after a thorough decarb, it has 104 psi on the top cylinder, and 106-107 psi. How to do a compression test on an outboard motor mrmaxstorey 47. Evinrude 70hp ideal compression?. No Results To Display. You might try a different compression gage, readings can be. 36 (61 x 60) Displacement - cu in (cc) L. 5‑14 Horsepower ‑ Evinrude/Johnson 9. This outboard engine weighs approximately 269 pounds. Easy-to-use parts diagrams Best price guarantee Expert live support 50+ years of serving boaters Huge selection of OEM parts - from 1950 to 2022 Most parts in stock - Same day fulfillment Where is my model number? Parts Diagrams: Select your engine to find guaranteed-fit parts. 1994 Johnson 225 hp outboard motor compression test - YouTube 0:00 / 0:00 1994 Johnson 225 hp outboard motor compression test yougazbuffytube 4 subscribers Subscribe 4 4. Taking a Reading with a Compression Gauge. Compression Test on Mercury 2. Evinrude Service Manual free download. Two-Stroke engines should have a compression reading of around 110-130 PSI. EVINRUDE® E-TEC® G2® 225 H. What is Good Outboard Cylinder Compression?. SPECIFICATIONS 100% Global Emissions CompliantEPA 2013 / CARB 3 STAR / European Union Variable Voltage Computer Controlled 133 Amp. Force Outboard Compression. Like 85-125, so you are really looking for consistence without knowing what year/hp you are working on. Powerabout adjusting the heads with gaskets to balance the compressions on a new engine is not meant to bring back compressions on an old engine. Yeah, that is pretty low for a 4hp, these engines have higher compression than the older 3hps. Pull all the plugs and test the compression, throttle should be open while cranking the motor, all should be within 10 percent of each other. April 19, 2015 at 2:44 pm #14276. Crank the engine with the starter or pull cord through at least four or five flywheel revolutions, or until the compression-gauge needle stops advancing. Evinrude Outboards. This 1976, 115 hp Evinrude is made for saltwater. Evinrude 4hp Compression Testing. Is the too good or are they too high? I used a brand new. Find the factory specs for the motor so you can compare to your readings. #1 I am looking at a boat with a 1988 evinrude, I asked about the compression and here are the results I was given: starboard block upper-115, lower-120 port block upper -108, lower108 and new water pump, intake strainer and plugs done a well. They don’t have ports like on the Two-Strokes. What Size Motor Does Your Boat Need?. A compression test is still the best test for a 2-Stroke engine and should be performed before any repair service is done on a 2 stroke engine. Your engine's RPM range is important in choosing the right propeller for a. The first is called a leak down test. frankr US Member - 1 Year Replies: 6473. What Outboard Compression TEST RESULTS Tell You! Born Again Boating 85K views 2 years ago How to do a compression test on small engines. Buying a used Outboard? What is Good Cylinder Compression? 6 Hp or 9. com%2foutboard-compression-test%2f/RK=2/RS=jDJO6tzcqEkbAAdGSVp8KL8YbTI-" referrerpolicy="origin" target="_blank">See full list on bornagainboating. Remote (Tiller accessory) Trim Method. 9K subscribers Subscribe 26K views 4 years ago Knowing how to perform a compression test is essential if you are buying or. i checked the compression on the 150 evinrude i got with the nice project boat i bought and the readings were 85, 80, 75 and 60i am gonna take the plugs out, run cleaner through everything and see what happens. Go (800) 209-9624 M-F 9-5 ET Each of these online catalogs offers application charts for Evinrude parts and Johnson parts to help you find discount. Those heads ran compression around 90+. ** 3 years of BRP Limited Warranty. Your 70 reading is low, even for these low compression heads. Take a compression gauge and thread the fitting into the number 1 spark plug hole. Apr 10, 2017 #3 RitcheyRch Currently Boat-Less Joined Sep 20, 2007 Messages 62,305 Reaction score 70,094 Thanks for the. #1 I have a 1975 Evinrude 70 hp. MODEL YEAR CHART FOR JOHNSON AND EVINRUDE 25 HP. i checked the compression on the 150 evinrude i got with the nice project boat i bought and the readings were 85, 80, 75 and 60i am gonna take the plugs out, run cleaner through everything and see what happens. Buy from the largest online inventory of genuine Johnson Evinrude outboard parts including discount aftermarket parts. 1980-Present: Evinrude outboards from 1980 to the present use a model number that can help determine the year and features of the motor. They have compact dimensions, easily transported and mounted on the stern of the boat. your 6 HP model # BJ6R4SOSM would match 6R4SOS in the chart, ignoring the " BJ " and " M ") 25 HP. 133 Amps Total / 50 Net Dedicated. WEIGHT - lb (kg) Single Slate Gray 20 (508) iSteer DPS H225HGLF 547 (248) Classic White 20 (508) iSteer DPS H225HWLF 547 (248) Single† / Multiple Slate Gray 25 (635) iSteer DPS IHS / Tiebar H225HGXF† H225HGXC‡ 569 (258) 558 (253) Classic White 25 (635. They dont 'suck' the mixture (at least not much) like a 4 stroke: the suction part takes place in the crankcase as the piston rises; as it comes down again it compresses it and forces it in to the cylinder when the ports open. Cylinder compression test of a low hour Johnson Evinrude 25 Hp Outboard Boat Motor An outboard has good compression if the values are above (roughly) 70 psi and are EV. Pre-1980: Evinrude outboards prior to 1980 do not have a consistent model number code. On the port cylinders I got 80, 76, 72; and starboard cylinders were all 72. com 184 Jones Drive Brandon, VT 05733 USA (800) 209-9624 (802) 247-4700 (802) 419-3055 Fax. Purchase a compression gauge and leakdown tester to go in your boat's toolbox and check cylinders a couple of times a year to ensure there is nothing unusual. 60 (92 x 66) Displacement - cu in (cc) L. It has a brand new water pump, and water pressure was between 20 and 25 psi at all times when running above idle. Four cycle outboard motors produce much higher compression than two cycles. 115 & 150 evinrude compression issues. Your Johnson Evinrude Outboard Motor Service manual will come to you in pdf format for a fast and easy download! After downloading your Johnson Evinrude Outboard Motor Service manual you can view it on your computer or print one or all of the pages needed. Compression pressures can vary from motor to motor depending on the static compression ratio. 1988 Evinrude 225 HP E225TXCC This 225 horsepower Evinrude outboard, manufactured in 1988, is a saltwater model. In situations like these, a compression check can indicate if cylinders are working or not. Evinrude outboard engines are lightweight and feature quiet operation. Some outboard designs will read well into the mid hundreds. Slow rotation will affect readings: I'd make sure the engine will rotate at least 200 rpm with the plugs in, then remove all 6 and restest. Screw your compression gauge into the first cylinder. Examine the plugs, inspect the plugs for inconsistencies in color and for sign of damage and corrosion near the tip. I didn't have a lot of time to troubleshoot it last. to Compression Test an Outboard Motor. Compression only tests a small amount of the cylinder with absolute certainty and the rest can be damaged. Make sure you position the throttle to the WOT (wide open throttle) position, it must remain there. This uses a special set of gauges. And when a head gasket wears out, it automatically causes poor compression in the cylinder. How to do a compression test on an outboard motor mrmaxstorey 47. evinrude/johnson never had a figure for the compressions on the engines from the factory, all they state is that as long as they are within 10% they are ok. Trac-1 Power Trim and Tilt. This engine has power steering and a recoil-type starter. com">Evinrude Outboard Motor Model Numbers & Codes. Once the reading is verified to be only 50PSI, I would pull the head. To sort chart by column (Year, Model, etc) click on the desired column heading. Location: Seattle Shorewood Bob Junior Member I just tested the compression on this Evinrude 115hp. There are two basic ways to compression test an outboard. Your Johnson Evinrude model number is the key to finding the correct parts for your outboard motor. Compression testing a two stroke tells you very little about the state of the engine. Not necessarily the hp or size. The type and model is what matters in an outboard’s compression readings. Sometimes having compression as low as 80 and 90, the engine will still run great! We’ll talk about low results in a minute. Evinrude E-TEC OUTBOARD WILL NOT START OUTBOARD HARD TO START OUTBOARD WILL NOT SHUT OFF OUTBOARD STARTS AND STALLS OUTBOARD STARTS, LOW MAXIMUM RPM EXCESSIVE SMOKING OUTBOARD SURGES, RUNS ROUGH MWS Instrument Wiring Harness Lanyard Switch / Emergency Stop Circuits MWS Key Switch and Nuetral Safety Switch CANbus Keyswitch/TNT Wiring Harness. The engine weight is recorded at 101 lbs. As we continue to support our Evinrude engine owners, learn more about our focus and commitment to our customers as BRP prepares for the next generation of marine technology. Don't forget to request a quote to talk to your nearest Evinrude dealer on more details on your engine choice. See the model number information below for your engine. Your Evinrude outboard model number can usually be found on the nameplate located on the motor or the mounting bracket. Low Hour Evinrude 25 Hp Compression Test. In situations like these, a compression check can indicate if cylinders are working or not. How to Compression Test an Outboard Motor. Compression is about 125 psi on each. Evinrudes have a wide range of compressions depending on year and HP. Have the dealer perform a leakdown test, this can tell you the actual condition of the engine. I just checked the compression on all 3 cylinders and it is 150# on each. #1 I am looking at a boat with a 1988 evinrude, I asked about the compression and here are the results I was given: starboard block upper-115, lower-120 port block upper -108, lower108 and new water pump, intake strainer and plugs done a well. Lion hunter Lieutenant Commander Joined Apr 9, 2005 Messages 1,529 Jul 11, 2010 #3 Re: 70 HP Johnson compression test. A compression check can indicate that the piston rings are working properly and that the cylinders are in good condition. E-TEC Direct Injection with stratified low RPM combustion mode. Hopefully just a blown head gasket. The model number will identify the year and certain details of that motor. Does a compression test alone always determine that my outboard is in good shape? Suprisingly the answer is "no". The type and model is what matters in an outboard’s compression readings. low compression is also cause from stuck rings, in there seats on the piston, debarbing removes the crap sticking the rings. See our model number guides for help. 1978 Evinrude 115 (115893C) Compression Check. Once you get it about 1/2 unscrewed you can hold onto the bolt head and unscrew the latch lever. Shortly after a thorough decarb, it has 104 psi on the top cylinder, and 106-107 psi on the bottom cylinder, when taken on a warm engine. Now the inner actual latch can be pulled out after it falls off the screw, which then the screw is free. Taking a Reading with a Compression Gauge. Screw your compression gauge into the first cylinder. Everybody hears about performing an outboard motor compression test, and everyone knows that when you buy a used boat, you should compression test the outboa. 5 Hp Carburetor Rebuild; 25 Hp Water Pump Replacement - All Models 1985 to 2005 ; Johnson / Evinrude Lower Unit Compatibility Chart. Outboard Motors & Engines, Parts and Accessories | Evinrude US | Evinrude US. Yamaha Outboard Compression Evinrude Outboard Discussions 4-Stroke Bracket Cable Carburetor Code Color Compression Condensor Cooling Cover Crankshaft Cylinder Dealer Diagram Drive Electric Engine E-TEC Exhaust Ficht Flywheel Fuel Fuel Pump Gasket Gauge Gearcase Identification Impeller Key Keyswitch Leak Loss Lower Unit Marine Model Number New Oil. Due to the presence of the E-Tec direct injection system, boat engines are highly economical, since the fuel is supplied directly to the combustion chamber, where it is layer-by-layer burning. And when a head gasket wears out, it automatically causes poor compression in the cylinder. The nameplate should contain a model number and a serial number. Compression : Compression on these motors may seem lower than some of the others. i ran it with gas mixed with mucho …. There are two basic ways to compression test an outboard. Purchase a compression gauge and leakdown tester to go in your boat's toolbox and check cylinders a couple of times a year to ensure there is nothing unusual going on internally.