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Can it be head gaskets? (E140TLENS,1992 140hp v4)

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Greetings from DownUnder. (E140TLENS,1992 140hp v4). Got the boat about 2 months ago. Didn't run for 15 years. Got it for a bargain. Re-dit lower unit because it wasn't pumping and there was water in lower gear unit. Didn't start at first. Wen't over fuel line and changed what I could. Got it to start but it was overheating. Ripped off cylinder heads and started cleaning.(Not too bad actually) Put everything back and it runs like an ostrich. Vro is removed and I premix. Everything is good BUT;
I used the same head gaskets again because they really still looked good. The engine also. Today I did a compression test and all 4 cylinders is exactly 80 psi.(They should at least differ a bit). When I got the boat the guy said all 4 cylinders was 150psi. Which could be right if you look at the condition of the outboard. The cylinder sleeves also looked very good when I had the head off. The only thing that I can think of is that I didn't torque it enough (30nm), my torque wrench is not calibrated or the gaskets is leaking. Because they all give exactly the same reading(exactly 80 psi ). Should I torque it a bit more or just get new gaskets. The thought of torquing it some more gives me cold sweats. They are on the expensive side + postage to Australia. If I should get new gaskets, can I just get the aftermarket ones. Engine sounds great though.
 
I converted NM to ft lbs & 30nm (20-22 ft lbs) is about the limit as to where you want to go. If you said you were leaking water running the engine to temp & retorque may fix that. You could have used a little sealer on the gaskets (since they are used). OMC/BRP gasket sealing compound or Merc Perfect seal. Permatex makes an aviation cement adhesive that can be used.

I think with a little running the compression may come up. 80 is low, but 150 would be high for this motor so the gauge may not be accurate. Yes the fact that they are even is good!
 
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Hi t2stroke. This outboard doesn't have diverters. I did put a very thin layer of omc gasket sealer on front and back of gaskets. So you suggest going to 31 nm. Just a thought, the top 320936 — SEAL, EXHAUST HOUSING did not go on properly when I put back the lower unit. Could this also contribute to the problem. I also though 150 was high.
 
I let the outboard heat up to temp in a wheelie bin before I took the reading. Removed all 4 plugs and tested. I also read that it could be stuck rings.
 
I edited my comments as I first thought we were dealing with a cross flow. Obviously a looper! No diverters. Loopers were not so bad about sticking rings just thought it might take a little for things to settle in. Maybe not? If it starts well & idles OK, I wouldn't worry about the 80 lbs compression for now. Highly unlikely they would all be exactly the same from wear or other problem.
Your exhaust seal is a common problem. If you can glue it in place on what I call the shoe (inner exhaust piece). After it dries I put a little lube around the outside edge which helps it seat in place. That seal helps control your wall of water inside the exhaust housing. Nice to have for the health of the water pump.
I do not believe I would go any higher on torque. Just retorque after repeated heat cycles. Those gaskets should seat again.
 
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I actually closed my eyes and retorqued it to 31 nm before i saw you're post. Bolts still good, phew. It was a cold compression test but it went up to 90 psi. Does that mean new gaskets or just because of cold test. As a matter of fact I will heed you're advice and just go with it as is. The outboard was running at most for 30 minutes on and off after 15 years. Maybe just a good little workout is all it needs. If the compression doesn't change after a while I'll just get some new gaskets. I appreciate all your help and getting back so quickly. Cheers mate. By the way thanks for the lower exhaust seal advice.
 
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Check the compression on your lawn mower if it is also low the tester may be wrong. Or borrow one from your local auto part store and compare readings? If you put gasket sealer on the head gaskets you may regret it time will tell i guess. If its running good give it a good decarb. Get a can of seafoam spray and on the water bring the engine up to temp then at high idle speed spray the seafoam evenly in the carbs until it starts smoking real good and quickly shut it down. Fish for 1/2 hour or so then start it and run WOT for at least 20 minutes . The next day check the compression cold and see if the numbers improve?
 
Gasket sealing compound will not hurt head gaskets. The reason OMC put "Do Not Use Sealer" on the gasket is because it was not necessary. The mechanic is going to put the head gasket on & start the motor. Bringing the temp up & setting the thermoreactor compound on the gasket. Hopefully retorque.
The factory used sealer due to there inability to pass leak test because the engine had not been run yet, therefore the compound had not been activated.
Later assembly techniques were changed so that the engine was run before leaks test were done. The sealer is messy & hard to paint powerhead with it in place. This new assembly process allowed them to do away with the sealer. If you live in salt water area you soak the bolts, threads, & stuff in GSC in hopes of taking the motor apart later.
I am more of an OMC/BRP Engine Tuner or Merc Power Tune product guy than Sea Foam, but each to his own. I would leave it in over night, but it needs to be run within 24 hrs.
Dont know what your emmision rules are down under, but you might want to do this at night? HA!
 
All good advice, thanks. I think I'll do a seafoamy thing on a Monday night on Burrendong lake and report back after doing another comp test. Thanks for the help you guys!
 
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