Low compression in three cylinders

[ROKuberski]

I have a Fairlane 500 with a 292 that was rebuilt in '96.  The car was driven a little and then the owner died and it sat for some number of (unknown) years.  I bought the car last spring.  It starts well and run's okay, but at idle it is very rough.  I found that three cylinders were about 90 compression and went to about 125 with oil added.  The 160 compression for this engine at sea level is 130 for where I live at about 5,400'.

If you removed the plug wires on the three low cylinders, there was no change in rpm's.

I am tearing the engine down now and just have one piston out at the end of today.  I found that the compression ring was in the middle position instead of the top position.  Cylinder and piston looks great.  Does it seem likely that a mistake like this would cause such low compression?

I don't know what else to check for.  I have all new rings and will use a glaze breaker in each cylinder before reassembly.  I can only hope that this solves the problem.

Also, I have a leaky rear main.  I haven't removed the seal yet, but I am pretty sure that it is not the rope type, but a more modern one.  I have a two piece one in my Fel-Pro gasket set.  Do you know if the seal on the rear main can be replaced without removing the crank?

Thanks,

Rich

[Hoosier Hurricane]

While it's down, check the valves in those cylinders, they may have stood open for those storage years and the seats may have rusted.  The ring mixup shouldn't have caused a huge drop in compression to the point that the cylinder wouldn't fire at all.  The rear seal can be replaced without removing the crank.

John

[ROKuberski]

John,

When we did the compression test, we did a wet test also and that brought the compression way up, so it is felt that the problem was in the rings.  I will have the valves checked, but there does not appear to be any rust in that area.

Thanks for the information on the seal.  It sucks that I have a leak, but now that the engine is mostly torn down, I want to correct that problem.

Rich

[Roger]

Rich,I am one that dont trust very many that rebuilds engines or calls theirself a mechanic.Rebuilding an engine takes extreme cleanliness and carefulness.(Plastigauging bearings,micrometer on cyl. walls and etc.)After already finding a major mistake like ring placement if it was mine and I already went as far as you have I would go through everything and make sure it is right.Yes it's a job and money taking the crank out and checking but it might pay off in the long run.That's just my input.Roger

[ROKuberski]

Roger,

All I know is that I have the original receipt for the work done on this engine in '96.  It is a comprehensive list of work done by the engine re-builder.  I won't have time to do more work until Friday (I'm retired, but tomorrow is my volunteer day at the Colorado Rail Road Museum where I am assisting with the rebuilding of an 1896 steam locomotive.)

The one piston I have out is in great condition.  I noted that the compression ring was not on top.  That is my assumption of where it should be, but frankly, that information is not in the instructions provided with the rings (Hastings) not in the 1957 Ford Shop Manual nor in the 1958 Motor's manual that I have.  If it's buried in one of these books, I haven't found it.

I know the car had minimal use before the previous owner died.  The car then sat unused for quite a while.  I will take the heads to a shop to have the valves examined, but I don't think they are the problem since the wet compression test indicated a ring problem.

I am certainly no expert, but I am a fairly decent shade tree mechanic.  I would like to see something obvious that was causing this problem, but preliminary indications are very vague on what's wrong.

I'll keep you up to date.

Thanks for assistance and guidance,

Rich   

[ROKuberski]

It's Saturday afternoon and I am making great progress.  When I removed all the pistons, I had two cylinders with what appeared to be minor surface damage.  However, after I honed all cylinders, there were no marks left on them.  They all came out clean and smooth.

I solved the mystery of the rings.  On the flap of the box, it tells where each ring goes.  I did not notice this when I opened the box.  The ring with the dot, the only ring with a taper, is the middle ring.

I also got the old rear main seal out and the new one in.  The previous installer did not make the 3/8" offset between the joints in the seal and the retainer.  I hope that this goes a long ways toward making a leak free engine.

I won't be able to get back on this until Monday, but then I will clean and re-ring the pistons and clean and paint some of the engine parts while I have them out for easy access.

Things are going well and I sure hope that I've solved my low compression issue.  I was speculating that there may have been some rust in the cylinders with low compression, but I will never know for sure.

Rich

[ROKuberski]

Well, the rebuild is now complete.

I got everything back together Wednesday evening and took a short test drive before going to bed.  As of Friday, I have about 30 miles on the engine and it is now idleing fine, starting well and shows signs of more pep that before.  Tomorrow, I will get it hot again and readjust the valves, (I can hear some clatter.)  I'll also confirm timing and dwell, but they should not have changed.

Preliminary indication is that the leak from the rear main is solved and no new leaks have shown themselves.

Now I'm on to seeing what is causing my vibration at about 65 mph.  Yes, tires are ballanced.  The front end appears to be in generally good conditon.  I've replaced the front universal joint too.  That had rusted needle bearings and I was hoping that this was what was causing the vibration, but not so.  Anyone have any brilliant ideas for me?

Thanks,

Rich

[Alex L.]

Transmission causing the vibration?

[ROKuberski]

I suppose that is possible, but I don't know how to verify that.

I am hoping it is something that I can correct.

Rich

[Ford Blue blood]

Automatic or manual?  Rear u-joint?  Drive shaft straight and balanced?

If manual check to ensure there is a bushing in the end of the crank for the snout of the transmission to fit into.  Check the "up and down" play of the slip joint, should be as snug as a bug in a rug, no play at all.

[ROKuberski]

It's an automatic with a new u-joint in the front.  When I replaced the front u-joint the rear seemed tight.

As to ballance, the only way I know to check that is to take it to a place that can do that.

I will check the play in the slip joint tomorrow.  If no play, I'll look into having the shaft reballanced.

Rich

[Ford Blue blood]

Rich just happened to think of one other item to check....make sure the rear u-joint is the correct joint.  The 60 wagon I got this past summer had the wrong one in it.  Drive shaft would move side to side in the cups on the rear end (only 1/16th but that would be more then enoupf to make it shake, rattle and roll.

[ROKuberski]

I got under the car this weekend and did find that there is some movement when you grab the yoke at the tailshaft and yank hard on it.  Movement enough that I can feel it.  It is at the spline shaft area, not the new u-joint I installed.  I haven't looked yet, but I hope this part is available.

I also looked for leaks on the oil pan, rear main seal area.  No leak at the pan, but there was a drip on the oil pump, a part that I did not touch.  There was also a drip on the bottom of the cover for the flywheel.  Could be from the oil pump or the rear main still drips a little.  Regardless, I've got a 99% reduction in engine leaks.  I guess that I will be able to live with this.

Rich

[Ford Blue blood]

There is a bushing in the tail shaft that will wear out over the years, should be readily available.....and check the yoke as well but they are not the issue usually.

[ROKuberski]

I pulled the tailshaft housing last fall to replace the rear seal but did not notice a bushing, however I was not looking for one either. 

I was also thinking that I could be bending the tail shaft a little when I was pulling/pushing on it trying to determine if there was any play.  It must be a foot long inside of the tailshaft housing.  I found a drawing on the internet and I do see what appears to be a bushing that rides on the outside of the yoke as it is inside the tailshaft housing.   Is this the one you are refering to?

Rich