Nailhead/Compression HELP!!!

Okay, here's the deal guys;
I Purchased a 63 Buick Riviera w/401 nailhead motor, on Monday in Salt Lake City, with plans on driving it home to Boise (about 300 miles). Now i had heard the motor run before and it sounded great! There was no oil or tranny fluid anywhere to be found on the motor or on the driveway, all the fluids looked good. The PO assured me that it would make the drive to home (for what it's worth he seemed like a pretty honest dude...)

ANYWHOO... I hit the road Monday afternoon. It was a cool 100 degrees out and she was running great! Then at about the 60 mile mark i see smoke. I immediately pull over and see that there is oil all over the right side of the motor (pass. side), and at lower rpms the engine was breaking up. I was missing about half a Quart of oil.

Come to find out I lost compression in one of my cylinders. After getting her home i am pretty sure that the oil was just coming out of where the dipstick goes into the motor, because it doesn't want to seal in there at all, it just kinda flops around, and i haven't lost a drop of oil since then. The oil still looks good, no gas or coolant mixing in with it as far as i can tell.

As for the sudden loss of compression: Please bear with me, I am no expert on motor's by any means of the word, but i pulled the valve cover and started her up to see if anything looked awry, and saw nothing out of the ordinary. If a valve were stuck open would i not be able to see that? My plan is tomorrow to blow some air in there to see if i can find where it's escaping from (Intake Valve, Exhaust Valve, or rings).

So what else should i be looking at here? Am i totally screwed? Cracked head? Cracked cylinder?

Any advice/guidance/words of encouragement would be greatly appreciated!

-Ryan

 

Sit back and think a minute here and it will come to you.

Oil blown out the dipstick tube or out the breathers happens either because the crankcase ventilation system isn't working right or you have blowby past the rings.

Check the pcv system and make sure everything is intact and working. A new valve is under 5 bucks most of the time.
Then run a compression test and the leak down test you had planned on and see what happens.

My best guess is that you are going to have to do a ring job on it before long.

Unless it is loosing coolant you most likely don't have any cracks in the heads or block.

 

^^^
What he said!
The dipstick should have a little rubber piece that holds it in the hole. You could get blowby from there. But I believe you need a ring job!

 

Genius! Why didn't i think of that?

 

Hold up, the only problem with that, is that there is no smoke out the exhaust. If that were the case i should be smoking out my tailpipe right?

 

'63 should have a road draft tube. make sure the tube isn't plugged. if the tube is plugged and you are getting enough pressure to blow oil out the dipstick you are no doubt blowing oil past the 50 year old rings. At the very least you will be getting ring flutter and that will cause it to break up.

next or while you are at it do a compression and leak down test and see where you are at.

 

Yeah, your first order of business is to do a compression and leak-down test.
That will either reveal the problem, or it will cross off one of the big possibilities.
After that, start checking gaskets, ventilation system system, etc.

You're dealing with an old car, too... remember that the oil smoke and the engine breaking up at low RPM could be two entirely unrelated problems. Smoke could simply be hot oil leaking onto the hot exhaust pipes, and the dipstick tube may not have it's rubber grommet anymore.

Sources of oil leaks could be the valve covers, timing chain cover, oil filter housing.

How have you determined that you've lost compression in one of the cylinders? Are you absolutely certain that you've lost compression in a cylinder, or are you just guessing?

If you'd like to narrow it down, if you don't have compression, you're not going to have much ignition there... a cylinder that's down will have a cooler exhaust port. If you let the engine just idle for a few minutes to bring all the cylinders up to temp, if one of your exhaust ports is cooler than the others, you know that's the cylinder with a problem.
That's easier on headers though. But it's cheap, easy and requires no tools.

-Brad

 

That is what i was thinking originally.

Well when she broke down i had nowhere to leave it for a couple days while i figured out a trailer situation, so i left it at the dude's house i bought it from. He did a compression test on it for me and was able to determine which cylinder had gone.

-Ryan

 

No pcv...

yep...

Yep.
He says he knows which cylinder lost pressure, But I'd still do a compression check on all cylinders, then a leak down on the offenders. Then you will know specifically where the issue is...

 

Ah.
Well then, that certainly narrows things down.
You could have bent a valve for some reason, something very tiny could be hung up in one of the valves.
If it's not backfiring through the carb, then I'd look to an exhaust valve.

Check the end of the spark plug--look for it being wet or smashed.

That's about all I got.
Sorry.

-Brad

 

Well I popped the intake and the valley cover off last night to find that the cylinder in question does indeed have a stuck valve, also on the other side of the motor is a bent rod.

PO said he only checked the compression on the side with the oil on it, thinking something had busted thru on that side.