Compression readings not so good on gas engine.

[Roto]

Well this is the situation. I have a 1969 model 2544 (544) international tractor with a C200 4cyl. gas engine. The tractor has been worked pretty hard but only has 1300 hours on tractor. all original never been rebuilt. I did put a head gasket on it a few years ago i think other one was leaking by. Anyway The hydro may be going as well so i dont want to put a lot into this at this point. I changed plugs and wires and distributer and the plugs had a caked on material like ash build up or carbon or something that was built up pretty good. Color was great and gap was good but just some deposit build up of some kind. I checked the compression. manual says i think 180-185 is what it should be. I had number one =165 number 2=145 number 3=75 and number 4=125 as you can see its not good. the number 3 at 75 worries me. The 2 plugs that looked the best were the 2 worst cylinders. the best compression cylinders had spark plug build up. go figure. anyway, Im thinking stuck rings or hoping anyway. is there a way to check to see if its the rings like putting oil in and re-checking compression? Also could it be head gasket or valves? i will say that tractor runs smooth as can be and is very quiet and no noise coming from engine. It runs good but im sure it doesnt have the power that it should have. If its stuck rings, Is there a fluid to put in to eat away any bulid up to free the stuck rings? If its just broken rings or something I wonder if just a ring change would be enough to help it? i really dont want to do a motor job. I may try just rings but thats about it. I would rather try a cleaner or additive that would help the stuck rings or enhance the compression if there is such a thing. It may be just a valve but i would thing i would here noise? Also there is breather tube coming out the side and i felt it while engine running and got nothing coming out at all. There are some oil leakes here and there but could be just valve cover or other gaskets its hard to say. if anyone could tell me what they think it could be and cheap quick fix or test would be great.

thanks
Mike

 

[Charolais]

Hi Roto. What I'm about to write here some will frown on. But That's OK. /forums/images/graemlins/laugh.gif

I have a 1980 Chevy truck that belonged to my Dad. It was used mainly on the farm for all those years. It's got about 125,000 miles on it and back about 91 we just put Farm Use tags on it. So it only gets used for minor duties on the farm now. !999 I was fencing a lot of land in because of drought. Used that truck every day. It started going down hill with the power and by fall it wouldn't go over 30mph and couldn't back up a small hill. First thought was it's time to junk this thing. It's rusted out pretty bad and no need in spending money on it. So I parked it.

About a month later I was in Walmart I think. Saw some engine restore product. I said to myself this would be a good test to see if this stuff works. I bought one can for a V8 engine, changed the oil, filter and dumped it in. Got it cranked up and started to the local country store to get some fresh gas. Couldn't get over 25mph in that 5 mile drive. Put in 10 gal. of mid grade and hit the road. I put the pedal to the bottom and held it for maybe 5 miles. It started getting a little faster by then. I drove it another 15 miles and it kept gaining power. By the time I got back home that truck would run 80mph and all the skipping and popping was gone. Got the oil pressure back up some and oil consumption went down. It worked. That truck is still running today. The truck already had Bosch Platinum plugs in it. And they cleaned up nicely after running the engine restorer in the engine.

Now this may not work on any and every engine but it sure worked on that 305 Chevy. The way I looked at it the truck wasn't worth spending a bunch of money on but for 9 bucks hey it's worth a try. That's the only engine I ever used Restorer in but if I need it again I'll sure buy a can and pour it in. It sure isn't going to do an engine any harm that lost compression and just running poor. That is if you don't want to put a bunch of $$$$ in for a total rebuild.

All this is just a suggestion and what has worked for me. Here's a link for the product. http://www.restoreusa.com/restorer.html

 

[EddieWalker]

I'm sure a real mechanic will jump in here and straighten me out, but for now, I'll offer my opinion.

When you check the compression, remove all the spark plugs. Check all the cylinders one at a time and write down the results.

Then do them all again one at a time, but this time squirt a little oil in the cylinder first.

If the reading increases, then you know it's the rings. If not, it's the valves.

As for a "stuck ring," I'm not sure what that means. Rings wear out mostly, occsionally they break, but getting stuck doesn't make sense.

A more likely scenerio is the valve stems are wore out from using modern unleaded gas in an old engine designed for leaded gas. The unleaded fuel doesn't lubricate at all, which causes them to wear out much faster.

Another test is to hook up a vacume guage. If the vacume isn't steady or surges, thats another good sign it's the valves.

Your one cylinder is way low, but if the engine is running, I wouldn't do anything to it until you have to. Figure it's already bad, not much more damage can be done if you keep running it.

Besides, why put money into rebuilding three good cylinders, when only one is a little week?

In my opinoin, change the oil, keep an eye on it, and run it like it is.

Eddie

 

[Roto]

Im no mechanic either but stuck rings would be from build up that could cake on the rings and keep them from springing out against the side walls or in probabbly most cases overheating and bonding it to the piston so it loses its springing effect. i have heard of stuck rings quite a bit. I wonder if there is a spot for a vacuum guage on that tractor?

Mike

 

[AntrimMan]

Not an expert here by any stretch but unless you cooked the engine till it seized or run it without oil or left it exposed to the weather I just can't go for the stuck rings. Don't be worried about major discrepancies in the compression check, it's not like it's life support equipment. If it runs as smoothly as you say it does there can't be anything major wrong with it. Run the snot out of it and be happy you have it.
On the other hand, just what was the reason to do the head gasket in the first place?
A burned valve won't necesarily make any noise and you have to see the seats to be sure unless the bugger is pretty badly burned.
Did you touch up the valves and seats while the head was off?
Did all the components go back in their original homes?
Were you as clean and neat as you should have been?
Did you adjust the valves when the head went back on?
Did you make sure the head was getting enough oil?
Are these engines known for bad cams?
I have seen well meaning gentlemen think they were doing the right thing by taking the ridge out of the bores while they had the head off. If you did that I bet the rings are broken as they aren't meant to flex that much that quickly and will fatigue and fracture.
Yeah, some oil down the bores raising the psi will indicate worn rings if there is nothing else wrong but you say there is no blowby or major pulses from the breather tube so rings are doubtful.
It's easy to tell if a cylinder is weak on a gas engine. Pull all the plug wires and leave them loose on the pulgs. Start the engine. One by one lift the plug wires slowly away from the plug. You can hear a good spark if there is one. You can tell if the spark crossfires in the cap. You can tell if the plug is fouled. You can tell if the wire is a leaker(ouch). With the wire far enough away from the plug the cylinder will miss and with your hand on the valve cover you will feel the difference. If there is little change in the engine idle smoothness you may have a weak one and need to find the cause or ignore it.
You can pick up vacuum at any port below the throttle plate.
A decent gauge is not expensive and will offer some instruction on its use.
I wiuld say that if you don't rely on the machine for your livelihood and the plugs aren't fouling don't worry about it.
BTW, a compression check should be done with the throttle blocked open and the gauge should be screwed into a clean plug hole, the tapered rubber stem type gauges are difficult to use, the threaded ones are easier IMHO.
Hope this helps,
Martin

 

[mrcaptainbob]

I second all those great suggestions. Would like to add one more. You mentioned about the oil leaks. Clean the engine. Especially around the headgasket seam. If it's leaking, you may be able to see where. You could spritz some soapy water along the seam line when doing that compression check. If it's leaking to the outside and not across cylinders, then you may see the bubbles.

 

[normde2001]

I believe I would just drive it.

 

[ronnie2005]

Roto,

Over the years I have done several repairs for customers whom couldn't pay for the book repair.

Something that has worked several times on old engines. Pull the plugs and put 4-5 squirts of GM Automatic Trans fluid in each cylinder. Put the plugs back in, NO wires, turn it over with the starter for about 10sec.

Next pull the oil filter and drain it. Put it back on and add 1 quart of GM Automatic Trans fluid. Start it up, it will smoke, but that will go away. Drive it around and get it hot. Check the compression again, if it didn't come up, it need rings and a valve job wouldn't hurt since you have apart anyway.

You may wonder why I said GM fluid? Dextron II and III are very high detergent and it will clean everything inside, ring groves, sticky valves, lifters and carbon in the combustion chamber. You mention that you have some oil leaks. This method will probably make them worse and might cause more. So be ready to change some gaskets.

 

[Nasty135]

Roto, Accurate compression test has to been with engine at operating temperature, Low compression on one or two cylinders isn't fatal but not desirable either: Our old astro van with well over 300,000 miles has low compression (50lbs.)on a couple cylinders but keeps on going. When getting near oil change interval (about a week) I usually add 1/2 Qt. trans fluid to flush (some what). Valve stem seals are gone(smokes on start up) but still don't add oil between changes /forums/images/graemlins/cool.gif

One quick test is running the tractor at wide open throttle then cut it right back to idle ,If it blows smoke at that point the rings are worn.
If it pops at idle ,probably burn exhaust valve.
You could try the engine restore stuff, Like said before it won't hurt.

As far as a ring job ONLY ,forget that unless your going to do the head (valves)also and hone the cylinders(new rings won't seat without fresh hone job.

As said before I would try a little tranny fluid and or restorer and run it..

 

[Roto]

Sorry I cant figure out how to change colors so these questions and answers are same color.

On the other hand, just what was the reason to do the head gasket in the first place? <font color="blue"> </font> I noticed it was blowing by oil but not that bad.

Did you touch up the valves and seats while the head was off? <font color="blue"> </font> No
Did all the components go back in their original homes? <font color="blue"> </font> Yes
Were you as clean and neat as you should have been? <font color="blue"> </font> Yes
Did you adjust the valves when the head went back on? Yes
Did you make sure the head was getting enough oil? Didnt know how.
Are these engines known for bad cams? Dont think so
I have seen well meaning gentlemen think they were doing the right thing by taking the ridge out of the bores while they had the head off. <font color="blue"> </font> I did NOT do that!
You can pick up vacuum at any port below the throttle plate.
A decent gauge is not expensive and will offer some instruction on its use. <font color="blue"> </font> I have a guage and will see if i can find a spot below throttle plate.
BTW, a compression check should be done with the throttle blocked open and the gauge should be screwed into a clean plug hole, the tapered rubber stem type gauges are difficult to use, the threaded ones are easier. <font color="blue"> </font> I have threaded type guage and checked several times and made sure clean and tight. I was hoping it was only a bad seat hehe As far as throttle i didnt change that it was probabbly down some but you say i should have throttle wide open when checking compression?

Another note I may add is that it smokes a little at start up but thats about it as far a smoke goes.

I am gonna check compression again with oil and check vacuum if I can and get back to you

Mike