compression.test

[Davidmerc140]

I just compressed tested my engine and I receive various readings from 60 to 80 p s I mercruiser 140

 

[Grub54891]

Re: compression.test

Serial number,year would help. Did you have an issue with it running? Why the test? Them numbers are pretty low. Do a wet test also. That will tell you if it's rings or valves. Them engines are usually pretty good units in my opinion. I just got one this summer and it gets me around the apostle islands real well! Mines a 1985 ,haven't run the compression test yet but I work on mercruisers quite a bit at work,so I trust my instincts. I'm redoing this winter anyway,more of a re- fresh of the complete boat. Please get us more info.....

 

[thumpar]

Re: compression.test

Along with the above, what is the history?

 

[Davidmerc140]

Re: compression.test

#3681706 yes i was having a backfire through carb issue turned out to be timing (distributer turned during operation i guess) its a 1970 sea swirl I purchaced it from a man who painted it and re did the interior. I replaced the gimbal ring resealed the upper and lower units bellows lower shift cable and adjusted the.shift cable/oh and control box was swapped out. It was running fine till a couple of weeks ago.

 

[tpenfield]

Re: compression.test

Post the readings for each cylinder (please) . . .

Also, did you have all of the spark plugs out during the test and was the engine cranking at a decent speed, etc?

I think your next step is a cylinder leak test, as that will tell you more about the source of the problem . . . now that the compression test has indicated a problem.

 

[Don S]

Re: compression.test

I just compressed tested my engine and I receive various readings from 60 to 80 p s I mercruiser 140

That engine is junk with those readings. Probably wouldn't even get it to start. Are you sure you did the test properly and your gauge is accurate? Anything below 100 is not good.
Here is a service bulletin on the proper compression test.

View attachment 97-25 Compression Test.pdf

 

[Davidmerc140]

Re: compression.test

Yea i didnt relize i had to follow procedure retesting tonight thanks

 

[Don S]

Re: compression.test

Yea i didnt relize i had to follow procedure retesting tonight thanks

Especially the part about a fully charged battery.

 

[888]

Re: compression.test

Anything under 100psi and you got issues. Give a squirt or two of oil in cylinder and retest,if psi picks up you have a ring issue and complete rebuild is in order. If it psi doesn't pick up with oil then you could have a stuck valve/s or blown head gasket.

 

[Davidmerc140]

Re: compression.test

Testing gave similar results where can i find rings/valves ect. online planning on doing the rebuild myself

Mercuiser 140 #3681706

 

[Bondo]

Re: compression.test

Testing gave similar results where can i find rings/valves ect. online planning on doing the rebuild myself

Mercuiser 140 #3681706

Ayuh,... It ain't quite that easy,...

You need to find a Machine Shop to do the work, 'n they'll tell ya what you need for parts...

It'll no doubt need to be over-bored, 'n new pistons..

 

[tpenfield]

Re: compression.test

Testing gave similar results where can i find rings/valves ect. online planning on doing the rebuild myself

Mercuiser 140 #3681706

Summitracing.com is a place that I have used for engine parts, etc. BUT as Bond-o said, it is not just a matter of getting parts.

If I were me, I would do a cylinder leak test to get a better understanding of where things the issues are before you start taking things apart, etc. That will tell you if you need to do a 'top-end' rebuild , 'lower-end' rebuild . . . or both.

Then there will be the 'discoveries' when you actually tear the engine apart. That is where you hope nothing is really busted.

Post pictures along the way

 

[Davidmerc140]

Re: compression.test

Having trouble finding any 4 cylinder rebuild kit there maybe napa?

 

[888]

Re: compression.test

This place here has never done me wrong. I dare you to try and find it cheaper.
Always super fast shipping too.

http://www.rpmmachine.com/shop/index.php?l=product_detail&p=748

 

[tpenfield]

Re: compression.test

Having trouble finding any 4 cylinder rebuild kit there maybe napa?

You will probably need various 'kits', depending on what needs to be replaced. The common kit will be the gasket kits, and often there is a cylinder head kit and a lower end kit.

You can also try MichiganMotorz.com

 

[achris]

Re: compression.test

You will probably need various 'kits', depending on what needs to be replaced. The common kit will be the gasket kits, and often there is a cylinder head kit and a lower end kit.

You can also try MichiganMotorz.com

and while you're at it, get a carbie kit, and an ignition kit. And a ring kit and a bearing kit. If it was mine and I was rebuilding the engine I would also make sure the starter and alternator are in top condition too, get the kits for them.

 

[Don S]

Re: compression.test

DO NOT order any kits for anything until you diassemble the engine and inspect all the parts. Without taking it apart you don't know cylinder condition or if you have to bore it, or how much, or if you will need the crankshaft turned which you would have to use other than standard bearings depending on how much it's turned.
There is a lot more to rebuilding an engine than just throwing some new parts in it.

 

[Davidmerc140]

Re: compression.test

Yea i called a machine shop today they qouted between 1500 and 2000
Still set on doing it myself accept the machining need a shop manual for this engine from there i will make decision to move forward or pay to have it done thanks for advice

 

[fishrdan]

Re: compression.test

greenbaypartsworld.com has rebuild kits for the 140 for around $500, probably another $400-500 in machine work if you do all the assembly work yourself.

As DonS said, don't order anything until you know what you need, pistons, rings and bearings will be determined by what machine work needs to be done, and how much they need to clean up.

I would do further testing to see exactly what the issue is, before tearing it down.

 

[achris]

Re: compression.test

Yea i called a machine shop today they qouted between 1500 and 2000
Still set on doing it myself accept the machining need a shop manual for this engine from there i will make decision to move forward or pay to have it done thanks for advice

Your wish is my command. Download and save this -> https://docs.google.com/open?id=0B1TAvwZ3TjhfZTgyNWM4MjQtOTdhOS00ODEyLTk1OGEtOGIwOGYwNzAwNGEz

greenbaypartsworld.com has rebuild kits for the 140 for around $500, probably another $400-500 in machine work if you do all the assembly work yourself.

As DonS said, don't order anything until you know what you need, pistons, rings and bearings will be determined by what machine work needs to be done, and how much they need to clean up.

I would do further testing to see exactly what the issue is, before tearing it down.

Completely agree with this. Until you strip the engine, keep your coins in your pocket.... did you do a cylinder leak-down test? That would give you a better idea of what's going on in the engine...

Chris......