Mechanics

NO COMPRESSION WHEN ROCKERS TIGHTENED

1998 Buick Century • 80,000 miles

I just replaced gaskets in a 3100 vin M engine with roller style rockers.
the push rods are right where they originally where before it was taken apart, when the rockers are tightened to spec there is no compression at all in any cylinder, if I loosen then so they are just hand tight there is compression and it sounds normal turning over.
there are 2 sizes for the push rods, one size for intake and one size for exhaust.
the rockers all look identical and all are in good shape.
i have no clue what I am doing wrong, any help in this matter is greatly appreciated.
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Pcdj64
June 8, 2012.



Really makes no sense then if everything is right you should be able to torque it and 30 degrees and it should be good.

Saturntech9
Jun 8, 2012.
The long rods go into the exhaust valve rockers, I wonder if I accidentally reversed one, I don't think it would be enough to kill the compression of the whole engine, just seems very strange.

Tiny
Pcdj64
Jun 8, 2012.
It would only effect the cylinder that it was reversed on. But if the rods were reverse tightening them down to spec would loose compression like your getting.

Saturntech9
Jun 8, 2012.
Push rods are in correct order, the remedy was to let the lifters sit and bleed out with the push rods tightened to 124 inch pounds, once that was done there was compression, apparently if the lifters expand with oil without the push rods they become solid until the oil is out of them where they can move again.

Tiny
Pcdj64
Jun 8, 2012.
Ok did you torque them the additional 30 degrees?

Saturntech9
Jun 8, 2012.
Yes, as close to 30 degrees as I could, they felt pretty tight.

Tiny
Pcdj64
Jun 9, 2012.
I have never seen a lifter do that on those engines.

Saturntech9
Jun 9, 2012.
Could be because of the anti freeze mixed with the oil, the mixture is harder to bleed out of the lifter than it is for just oil.
You take any of the lifers out and try as hard as you can to push them in and not one of them budges. What gave it away was the fact that whenever I would tighten a rocker the lifter had no give but the valve would move.

Tiny
Pcdj64
Jun 9, 2012.
Oh I see they were pretty much hydroloced that makes sense good catch you have a better view then I do though lol. Glad to hear you got it all figured out.

Saturntech9
Jun 9, 2012.
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