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.



So you added roller rockers which it didnt have before?As far as I know when you use roller rockers you must use a roller cam as well.

Saturntech9
Jun 8, 2012.
Original rockers are rollers, I only mention the type because some 3100 engines did not have them.

Tiny
Pcdj64
Jun 8, 2012.
Alright it says intake push rods are marked orange and are shorter then the exhaust ones. The exhaust push rods are blue do you have in the correct spots?

Saturntech9
Jun 8, 2012.
The intake and exhaust rods are where they were originally when it ran, the intake rods are a little shorter than the exhaust.

Tiny
Pcdj64
Jun 8, 2012.
Please tell me exactly how and what torque you set the rocker arms too?

Saturntech9
Jun 8, 2012.
Make sure the guides are lined up for the rockers to the head, tighten to 90in lb then I kept loosening until it got compression which was basically finger tight.

Tiny
Pcdj64
Jun 8, 2012.
Alright I have step one tighten them to 124 inch pounds then step two additional 30 degrees.
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Saturntech9
Jun 8, 2012.
So at 90in lb I should have had compression, I have to have them literally only finger tight otherwise 0 compression.

Tiny
Pcdj64
Jun 8, 2012.
How tight were they when you took the off?Why did you take it apart to just replace the rockers?

Saturntech9
Jun 8, 2012.
Typical for the 3100 it had blown intake gaskets and the gaskets have guides in them for the push rods so you have to take them out.
I don't know how tight they were, they were on there pretty tight.
80 or 124 inch pounds both would give compression, it right now with them tight has no compression at all unless they are just barely on there.

Tiny
Pcdj64
Jun 8, 2012.
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