Connected a vacuum gauge, doesn't look good

[sparky65]

Two weeks ago I started by 200 for the first time quite a few years. The previous owner claimed it was rebuilt by another previous owner. He had nothing to back that up with so i didn't believe him. The car ran fine though. About five years ago before I sent the car to be sandblasted I pulled the engine. I took the oil pan down, pulled the valve covers and it did look like maybe someone had been in there once before, but the timing chain looked slack, the oil pump pickup screen looked dirty and the freeze plugs were leaking. So I changed these things and sent the original carburetor out to get rebuilt. There was a different one on the car when I got it. I made a decision it wasn't worth pulling the heads. I repainted the whole thing and put it aside till I was ready to reinstall.

Surprisingly getting it started was fairly easy after we changed the points but it seemed to run a little ruff and there was some popping in the exhaust. Well I just connected a vacuum gauge and it seems to be oscillating pretty widely. I uploaded a video here: http://www.youtube.com/watch?v=QDS5rEcLCbQ
The shop manual seems to think this is a sign of a bad head gasket? Anything else I can check before going down to that level?

 

[66 E100 Pickup]

Could be head gasket, but more likely a sticking valve. The popping is a give away.

Do a compression check first, that should tell you what's up.

John/Fresno

 

[Frankenstang]

EDIT: John just beat me to it...good suggestions

IIWIYS the first thing I'd do is a compression test (dry & wet). A head gasket issue could be indicated by two side by side cylinders measuring lower than the rest. IIRC all cylinders should measure within about 10% of the others (eg if one cylinder measures 160 you'd expect another to be no less than 145. A single cylinder reading lower than that or very low, has a number of possible causes (damaged valve, stuck valve, rings...among others). For an engine that has sat for a good amount of time the first thing I would suspect is a stuck valve (a fairly common issue with these engines when they sit for long periods). I'd run a compression test and share your numbers with the good folks here for further diagnosis. Good luck!

PS always good to check for vacuum leaks as well
PSS cameras have come a long ways, but it can be difficult (for me at least) to discern how the engine is running via the audio...if you can post a longer clip and possibly rap the throttle during the clip it might also help...sounds a bit rough like you said but hard to make out for sure if there is a miss or what

 

[sparky65]

Did a quick compression check. By quick I mean the car had already cooled down. I didn't want to take it out and warm it up since it was threatening rain. Also I hate this loan-a-tool compression tester. No good way to tighten it in the spark plug hole. You have to turn the hose which slips before I think its sealed. All the spark plugs were out throttle was wide open. I cranked it 5-6 times per cylinder. First crank was about 30psi for each cylinder then it leveled out at the following:
cylinder->PSI dry -> wet
1->60->110
2->65->115
3->70->120
4->70->120
5->60->110
6->60->110

The numbers are so low its got me thinking the test is invalid and I'll run it again maybe tomorrow if the weather cooperates and I can warm it up first.
Here is a link to a longer clip you asked for. http://www.youtube.com/watch?v=pRxz3kqkdks The microphones on cameras are not great at all so I don't think this one is much better.

Edit: to include wet numbers

 

[woodbutcher]

The engine sat for a while.Soooooooooooooooooooooooooooo,you more than likely have some stuck valves and probably some stuck rings.
#1-Change oil and filter.Use 1 qt of Marvel Oil or your choice of additives as a substitute for one qt of regular oil.
#2-Start and let idle for appx 1 hour or u ntil lifters/valves quit ticking.
#3-Engine will probably smoke because of a little surface rust on the surface of the bores.
Don`t worry it will scour off,and not hurt anything,and the rings will reseat themselves.
#4-Been there.Done that for ALL of the above.
Good luck.Have fun.Be safe.
Leo

 

[rbohm]

8) first your compression numbers look fine for a cold engine, and they are even across the board.

second, it is possible that when you installed the new timing chain set, the cam got out of time. this could be due to an installation error, a tolerance stack issue with the timing set, or a combination of both.

third, since this engine has sat for a long time without being run, as the others have indicated you might have a sticking valve, gummed up rings, etc. there are a few options to try and deal with this issue. start by adding a can of marvel mystery oil to the engine, and run it for 20-30 minutes at idle or slow speeds, dont go over 25 mph. then change the oil and see what happens. if things get better, then run the procedure again. you might have to do it three or four times for best results. even if it doesnt get better after the first run, you should see a lot of junk come out of the engine.

if after a couple of treatments you dont get anywhere, then pull the head apart and clean the valves thoroughly. make sure the valve springs are with in spec, have the head gasket surface milled flat, etc.

 

[sparky65]

The engine sat for a while.Soooooooooooooooooooooooooooo,you more than likely have some stuck valves and probably some stuck rings.
#1-Change oil and filter.Use 1 qt of Marvel Oil or your choice of additives as a substitute for one qt of regular oil.
#2-Start and let idle for appx 1 hour or u ntil lifters/valves quit ticking.
#3-Engine will probably smoke because of a little surface rust on the surface of the bores.
Don`t worry it will scour off,and not hurt anything,and the rings will reseat themselves.
#4-Been there.Done that for ALL of the above.
Good luck.Have fun.Be safe.
Leo

#1 - I am always leery about these additives. Is some chunk of gunk going to come off and clog something up and cause a bigger problem. I am hoping the oil I added to cylinders for the compression test will lubricate the rings and I wont have to do anything. Am I too optimistic?
#2 - I only heard the valves tick when I first started it but that's been gone for a while. I don't think I hear it in the video, do you?
#3 - That's the confusing part. With this big of a change between dry and wet compression numbers I would think it would be smoking up a storm. No smoke that I can see. Also since the compression numbers are fairly consistent does that rule out a stuck valve? But the vacuum readings are pointing to good rings but a stuck valve. I guess that's why I am confused but maybe its a combination of everything like you say.

 

[woodbutcher]

Hi sparky65.Have used MarvelOil(R) or Rislone(R) on many occasions and have never had a problem.IIRC,the oil goes from the oil pump to the FILTER BEFORE it goes to the rest of the engine.So there should`nt be a problem there.If I am WRONG in thinking this,someone please correct me.The reason that I mentioned the rings eariler,is that sometimes,they will stick a bit in the ring grooves,and the oil additive will free them up.Some times there will be very little smoke from an engine that has not been run for a while.When I first started the engine that I installed in my truck(300ci) it smoked for about 20 minutes,and I thought"OMG"
I got a smoker.The smoke was light and then it quit.The only problem now,is getting around to replacing the valve seals.The oil that you used to do the wet/dry test should help loosen any slightly stuck rings.Hope this helps.
Good luck.Have fun.Be safe.
Leo