Evinrude 1957 compresion question .

Hi guys I just tested the engine and the reading is 30 psi on cylinder one and two . I did not do a wet test why bother with when its so low . I took off the head and the cylinders look good no scratched up or worn out . I able to rering it and restore the compression back to normal psi of over 100 psi . I dont know the cost of the rings and crank bearing seal and gasket kit . But I bet its under one hundred dollars . Can I reuse the some of the parts in this engine . I wish I could find a cheap power head . Well Thats why its not running right . It cant run on 30 lbs of pressure , thats why Im having a hard time starting her . Low compression . so At this point what can I do .

Re: Evinrude 1957 compresion question .

It won't run AT ALL on 30psi, and I've NEVER seen one with compression that low on both cylinders. Your gauge is wrong. I'd take off the intake bypass covers and see if the rings are still springy by pushing on the rings through the intake ports. If they are springy and you don't have a bad head gasket and the piston sides don't look too bad when looking through the intake ports, then your problem likely lies elsewhere. I suspect it does, anyway.
Check for spark on both cylinders with an air gap tester. If it won't jump at least a 1/4" air gap, then it won't fire at all under compression in the cylinder.
Good luck,
JBJ
BTW, you can buy rings and such possibly from seaway marine or elsewhere. But I doubt that's your problem. ALso, what model '57 are you speaking of???? If it's a 3hp, then it may be tough to find rings.

Re: Evinrude 1957 compresion question .

this is a double or triple post, but from reading them all i see that the head has been removed, with no mention of a new head gasket/ resurfacing the head or any re-torque of the head bolts???

Re: Evinrude 1957 compresion question .

I did check for spark and its good . Im getting good spark hot blue from the plugs . she will fire some of the time and run when she's warm and I can restart her . But the problem when she's cold it canbe hard to start . The cylinders look good the pistonare tight in the cylinders I cant move then side to side like a really worn out engine . I have seen engines worned out really bad before , but mine looks good for rebuild . I did a accurate reading with a good gage from harbor frieght so my gage is good , I cranked her 4 to 6 times and it never got over 30 psi .

I know the rings are worned out , I dont no why people on her are betting it being the headgasket, that was on ther tight and was never taken off ever as I can see .what do you mean by springy rings . the pistons are tight in the cylinders ,i can barely move then with my fingers . in the piston cylinder bores . They have a little play but not much . One of the member said I could have cracked block , how would I tell if I have one of them anyway . Im my problem lies else were them where do I look . I can only see it being bad rings on the pistons . I told the other members I had a large amount of black oil and gas in my water and Im using alot of gas to keep her running when I do get her to start . So I need to know why I dont have compresion of over at least 100 psi . I should get more thwn Im getting now , I did the compression test the right way . I worked on cars all my life and know that Im doing . A engine all work the same way , it run on gasoline and 13:1 compression rating or larger compression ratio .I do know that something is up with this engine . I can have the block checked for a crack if needed to .

Re: Evinrude 1957 compresion question .

rarely do you see compression that evenly low in both cyls ( or i have never). in my limited experience, one hole is usually somewhat higher than the other......unless the head was removed, and someone tried to re-use a 55 year old head gasket to save $10 bucks, or bought a new gasket , but didnt scrounge up a piece of thick glass and a sheet of sand paper to see if the head was warped, and take the hour or so to fix it if it was. jmo. start with the simple/cheap stuff, and dont over think the issue !!

Re: Evinrude 1957 compresion question .

Why should I check the head you tell me why . I would like to know why . Can I lose compression in the engine from the head gasket . How do you check it out . Would'nt you see or hear air from the head ?. As for the cylinders being bad Im not a expert so Only a machinest would know what the bore would look like if it was bad O can take a picture id you need to see for you self if you want me to . I did check for spark and she is hot . I placed the spare skark plugs on her and she sparked real good Hot blue/yellow color . I can see in plain day its getting spark . The engine will start on a engine with bad compression it will use gas like all hell . I had a old audi that had really worn out ring in the cylinders and I do mean worn out You could wobble the pistons in the bores . But My pistons are kind of tight in the bore , but that dont mean there not worn out .How do I know if the ring ant cracked you cant tell untill you take them apart to inspect them . Oh I forgot my motor is a 7.5 hp engine fleetwin

Re: Evinrude 1957 compresion question .

@nwcove

Your right about the cheap stuff first . Why wast a gasket when I can take her apart and do the job right the first time . She's 50 years old and may need so service , I dont know about the last owner and what they did to her . But its mine now and I really like her and want to fix it .There cool looking engines from the 1950's .

Re: Evinrude 1957 compresion question .

@jbjenning

My gage is not off I got a new one from harbor frieht today . I took the bad gage back to autozone today The first one would not give me a reading at all , the second one would not hold the presure . But the one from harbor freight was good . I tested the engine with that one and thats the reading I got , Im sorry but that the way it is . I did everthing right from the start to test the compression I worked on cars before and know how to test the compression on a engine . Plus or minus 10 0/0 is in the two cylinders the max you can have .You cant have like 40 in one and then 60 inthe other one . thats no good. If it jumps way up under a wet test then there bad . But being that my engine had 30 or maybe 35 on the second one . Thats to low of compression .Im betting on worn out rings , But I could be wrong too . I would hope its something simple like a bad reed valve or so . I dont know if bad reed valves would do that . Im not sure . But a cylinder leak down test would tell alot .

Re: Evinrude 1957 compresion question .

duckland23 said:

Why should I check the head you tell me why . I would like to know why . Can I lose compression in the engine from the head gasket . How do you check it out . Would'nt you see or hear air from the head ?. As for the cylinders being bad Im not a expert so Only a machinest would know what the bore would look like if it was bad O can take a picture id you need to see for you self if you want me to . I did check for spark and she is hot . I placed the spare skark plugs on her and she sparked real good Hot blue/yellow color . I can see in plain day its getting spark . The engine will start on a engine with bad compression it will use gas like all hell . I had a old audi that had really worn out ring in the cylinders and I do mean worn out You could wobble the pistons in the bores . But My pistons are kind of tight in the bore , but that dont mean there not worn out .How do I know if the ring ant cracked you cant tell untill you take them apart to inspect them . Oh I forgot my motor is a 7.5 hp engine fleetwin

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whoa duckland.....dont get yer feathers all ruffled!!. i read in one of your other posts that you removed the head and inspected the cyls, proper thing to do. but i did see no mention of you replacing the head gasket with a new one. and yes you can loose compression in your engine from a bad head gasket....or a warped head. ( you can fix the warped head yourself if its not twisted up to bad) . proper torque on the head bolts is also essential to keeping cyl pressure inside the cys. ....quote " Would'nt you see or hear air from the head ?"......if the head gasket was blown out completely you would see /hear air or water leaking, but thats rarely the norm.

Re: Evinrude 1957 compresion question .

So you would'nt see air or hear the leak . . Let me plac e a picture of it engine for you to see the bore in the cylinder walls . were else can you lose your compression from . Will bad reed valves cause a problem like hard starting too and low compression as well .

Re: Evinrude 1957 compresion question .

you have a few threads dealing with the same issue.....its getting confusing! if the head gasket is bad between the cyls it will show bad and even comp for both. as mentioned, dont overthink the problem......step back and think about it! ( and its not for me to say....but all your threads about the same issue are getting a bit confusing!!!....MODS???)

Re: Evinrude 1957 compresion question .

Pitures of the engine or powerhead witch ever you call it .

Re: Evinrude 1957 compresion question .

in the last pic, you can see how clean the piston to the left is.....good sign of a bad head gasket .

Re: Evinrude 1957 compresion question .

Ok maybe your right .

Re: Evinrude 1957 compresion question .

@Jbjenning

What do you mean by springy rings . I can push them down with a scerwdriver and they seem a little springy . They wobble a litle bit in the bore . On one of the pistons I can see some of the ring with my eye . Im told and know from past experince you should not see the rings at all , they should be tight and not seen by the eye at all . I can see some of it with my eye .

Re: Evinrude 1957 compresion question .

After reading the whole post, I think I'll leave this one with, No Comment.

Re: Evinrude 1957 compresion question .

duckland23 said:

I did check for spark and its good . Im getting good spark hot blue from the plugs . How did you check for spark? Did you use a spark tester or just ground them on the block? she will fire some of the time and run when she's warm and I can restart her . But the problem when she's cold it canbe hard to start . The cylinders look good the pistonare tight in the cylinders I cant move then side to side like a really worn out engine . I have seen engines worned out really bad before , but mine looks good for rebuild . I did a accurate reading with a good gage from harbor frieght so my gage is good , I cranked her 4 to 6 times and it never got over 30 psi . What I'm trying to get through to you is that your motor will not run AT ALL with only 30 psi, so either your test is not right, or your gauge is still not right. If you can't pull it hard enough with the recoil starter, you won't get a true compression reading. Until you get an accurate reading of compression, you shouldn't be deciding to rebuild it, especially since the cylinders look so good.

I know the rings are worned out How do you know??? , I dont no why people on her are betting it being the headgasket, that was on ther tight and was never taken off ever as I can see .what do you mean by springy rings I mean that when you push on them with a smalldriver, they will spring back . the pistons are tight in the cylinders ,i can barely move then with my fingers . in the piston cylinder bores . They have a little play but not much . One of the member said I could have cracked block , how would I tell if I have one of them anyway . Im my problem lies else were them where do I look . I can only see it being bad rings on the pistons . I told the other members I had a large amount of black oil and gas in my water and Im using alot of gas to keep her running when I do get her to start The black oil and gas in the water is normal. . So I need to know why I dont have compresion of over at least 100 psi Your motor didn't have over 100psi when it was on the showroom floor. About 80-85psi is what I get. I've heard of guys having really nice low hours 7.5's and they had about 90psi . I should get more thwn Im getting now , I did the compression test the right way Then your gauge is wrong---as I said, it won't run with 30psi. You would NEVER get it cranked even if you had a drill on the flywheel nut and a chainsaw motor running the drill. . I worked on cars all my life and know that Im doing . A engine all work the same way , it run on gasoline and 13:1 compression rating or larger compression ratio .I do know that something is up with this engine . I can have the block checked for a crack if needed to .

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My guess is that if you make sure the cylinder head is flat on a pane of glass, and that you install a brand new head gasket and torque the head down properly, you could get this motor running nicely with good spark, etc.. However, you are the one looking at it and not me, so if you say it doesn't feel right, you probably are correct. What does it feel like when you turn it over with the pull cord? Does it feel like it has good compression? When you turn the flywheel by hand with the plugs in, can you feel it compressing the air as the piston nears top dead center?
BTW, I had an '86 or so mercury 4.5hp single cylinder with all of the piston rings seized so badly in the lands that I had to pry them out and nearly ruin the piston-----it STILL made 60psi on my compression gauge (I have no idea how), and wouldn't even consider cranking no matter how hard I pulled it. Just sayin' I am totally confident it won't run with legitimate 30psi of compression.
If you had a cracked block, you most likely would have seen the crack by now.
Good luck with it. I don't have much to add. I hope you haven't had water spraying into the exhaust ports and washed all the oil off your rings, but I'd pretty much bet you'd have gouges in your pistons and cylinder walls if it did. When I say pushing your rings with a screwdriver, I mean from the side of the block, not from on top of the piston.
Hope this helps,
JBJ

Re: Evinrude 1957 compresion question .

@Jbjenning

I'll check it with a flat piesce of glass to see if its warped , How much play should the head have before its warped too bad . also is there any other gasket that can cause the compression to leak I can check also . I was wondering in the exhaust ports your talking about at the bottom of the piston to check if its springy . do I need to remove a gasket for that test .

Re: Evinrude 1957 compresion question .

Not exhaust ports, intake ports on the starboard side of the engine. Usually you can remove the cover without boogering up the gasket. You'll know if the head is too warped---cross that bridge when you come to it.

Re: Evinrude 1957 compresion question .

boobie said:

After reading the whole post, I think I'll leave this one with, No Comment.

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Dittto!