No compression #3

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mentalQtip
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No compression #3

Post by mentalQtip » Wed May 20, 2015 1:58 pm

'77 bus with fuel injection.
Rebuilt heads
New rings

This engine is from the local pickandpull. I've been trying to get it to start and run with little results. Got it to run briefly then wouldn't run at all(after I adjusted the timing again).
I checked compression and came up with
#1 135
#2 135
#3 0, 50, 30
#4 125

I'm thinking, "What in the world could I have done wrong? Then, what should I do before I just pull the engine again and take off the head?"

Joseph

mentalQtip
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Re: No compression #3

Post by mentalQtip » Wed May 20, 2015 2:56 pm

Tried looking at rockers while dear wife cranked engine. Looked fine to me.
Tried squirting oil in and cranking and read 135. Cranking again seconds later and read 0.
Does this pretty well confirm ring weakness?

Joseph

cegammel
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Re: No compression #3

Post by cegammel » Wed May 20, 2015 6:18 pm

'0' is something I haven't seen (which doesn't mean much...vast experience with TWO vehicles...)...I would actually look first at the compression tester and its fitment into the spark plug threads. Even with weak rings, you should get more than 0. The last engine I pulled apart was MISSING the top ring on the #1 cylinder...are you sure you put rings back on?

mentalQtip
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Re: No compression #3

Post by mentalQtip » Wed May 20, 2015 6:40 pm

Ok then. Went back and tried again. No oil. This time I see 5 lb.

Just squirted couple ccs of oil in. This time I got 60lb.

Is there any scenario that does not include pulling the engine? I don't see it.

Thanks

Joseph

cegammel
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Re: No compression #3

Post by cegammel » Wed May 20, 2015 7:07 pm

Let Colin weigh in before you do anything...but definitely try another valve adjustment before you pull it. If it isn't valves, and isn't the tester, then it looks like a pull is in the works. You may want to check head torque as well, but I doubt that would be this drastic.

mentalQtip
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Re: No compression #3

Post by mentalQtip » Wed May 20, 2015 7:14 pm

Thanks Cegammel.

I was told to check under cylinder 3 and see if any of the oil I squirted in there was dripping out underneath.
There just might be but it is very little. If I don't get contrary info from Colin I will just go ahead and pull it out again.(I was so proud of myself for getting it back in again by myself, too.)

Joseph

cegammel
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Re: No compression #3

Post by cegammel » Wed May 20, 2015 7:59 pm

I suppose that would indicate a blown gasket or improper seal? I would not have thought of that...again, my guess is that a drop of 135 to 5 would be a big leak. Keep us posted as you figure it out.

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Amskeptic
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Re: No compression #3

Post by Amskeptic » Thu May 21, 2015 5:56 am

mentalQtip wrote:Thanks Cegammel.

I was told to check under cylinder 3 and see if any of the oil I squirted in there was dripping out underneath.
There just might be but it is very little. If I don't get contrary info from Colin I will just go ahead and pull it out again.(I was so proud of myself for getting it back in again by myself, too.)

Joseph
Is this your personal rebuild effort that you are trying to start or a purchased engine sold as "new pistons and rebuilt heads"?

a) make very sure that the valves are adjusted correctly! Make sure that both #1 valves are moving in opposite directions as you wiggle crankshaft through #3 TDC area. Adjust #3 valves.

if compression still stinks, remove head and investigate both head sealing and ring gaps.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 94,615 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,990 miles

mentalQtip
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Re: No compression #3

Post by mentalQtip » Fri Jun 12, 2015 5:40 pm

Ok then. I did the stupid thing of pulling the engine and the 3/4 head and taking it to the local professional and he said the valves were not adjusted properly. So I put it back together and made "more" sure that the valves were adjusted properly and sure enough, we now have compression.

Sometimes I need to listen more.

Thanks

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Amskeptic
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Re: No compression #3

Post by Amskeptic » Sat Jun 13, 2015 6:28 am

mentalQtip wrote:Ok then. I did the stupid thing of pulling the engine and the 3/4 head and taking it to the local professional and he said the valves were not adjusted properly. So I put it back together and made "more" sure that the valves were adjusted properly and sure enough, we now have compression.

Sometimes I need to listen more.

Thanks
But the learning is priceless!
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 94,615 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,990 miles

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