NO COMPRESSION WHEN ROCKERS TIGHTENED

  • Tiny
  • pcdj64
  • 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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Friday, June 8th, 2012 AT 12:02 AM

19 Replies

  • Tiny
  • saturntech9
  • Expert
  • 29,311 posts

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.

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Friday, June 8th, 2012 AT 12:12 AM
  • Tiny
  • pcdj64
  • Member

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

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Friday, June 8th, 2012 AT 12:14 AM
  • Tiny
  • saturntech9
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  • 29,311 posts

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?

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Friday, June 8th, 2012 AT 12:21 AM
  • Tiny
  • pcdj64
  • Member

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

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Friday, June 8th, 2012 AT 12:32 AM
  • Tiny
  • saturntech9
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  • 29,311 posts

Please tell me exactly how and what torque you set the rocker arms too?

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Friday, June 8th, 2012 AT 12:41 AM
  • Tiny
  • pcdj64
  • Member

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.

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Friday, June 8th, 2012 AT 12:51 AM
  • Tiny
  • saturntech9
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Alright I have step one tighten them to 124 inch pounds then step two additional 30 degrees.

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Friday, June 8th, 2012 AT 12:57 AM
  • Tiny
  • pcdj64
  • Member

So at 90in lb I should have had compression, I have to have them literally only finger tight otherwise 0 compression.

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Friday, June 8th, 2012 AT 1:01 AM
  • Tiny
  • saturntech9
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  • 29,311 posts

How tight were they when you took the off?Why did you take it apart to just replace the rockers?

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Friday, June 8th, 2012 AT 1:11 AM
  • Tiny
  • pcdj64
  • Member

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.

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Friday, June 8th, 2012 AT 1:19 AM

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