Head Gasket replacement.
June 16th, 2015, 3:23 PM
#1
CF Beginner
Thread Starter
Join Date: Jun 2015
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Head Gasket replacement.
Hello out there. Was looking around for an Old's minivan forum and didn't find anything out there. I picked this Olds silhouette van up on 12/20/97 for only 26600. It's been a great van. Now it needs a head gasket job.
I am just now getting started on this and am having trouble getting to things on the back side of the engine. I hooked up a ratchet strap after removing the intake air hose and electric fans. The motor only tilted forward around 3 inches. Should I just put 500 pounds of pressure on this or is there something I am missing holding me back. This is going to be a very slow and easy project( Don't laugh to hard) I plan on only working on it 1 hour a day so I don't give to much blood while doing this.
I am just now getting started on this and am having trouble getting to things on the back side of the engine. I hooked up a ratchet strap after removing the intake air hose and electric fans. The motor only tilted forward around 3 inches. Should I just put 500 pounds of pressure on this or is there something I am missing holding me back. This is going to be a very slow and easy project( Don't laugh to hard) I plan on only working on it 1 hour a day so I don't give to much blood while doing this.
June 16th, 2015, 11:26 PM
#2
CF Beginner
Join Date: Dec 2014
Location: Washington State
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
Have fun with your heads
I did the head gaskets in 2012 on my 1998 Venture. I strongly recommend the Fel-Pro severe duty set HST9071PT (even for standard duty) with includes metal fire rings around the cylinder holes and most important includes the much improved lower intake manifold gasket with torque limiting discs (PermaDryPlus) instead of the standard duty failure-prone plastic LIM gaskets. It is a more expensive set ($123 at Rockauto) but the standard duty sets sometimes fail and as you will find out the labor is what makes this job fun (but you don't want to do it again).
As for rotating the engine it doesn't really move that much, hardly worth the trouble. I couldn't figure how I was going to get to the back cylinders but I just started taking things off, once the intake manifolds are off there seems to be plenty of room to get the back head off. I can't recall rotating the engine for anything important, maybe I did, I could do most everything without the 3" rotation you mentioned. I can't recall when in the sequence I disconnected the exhaust or if that helped at all on the rotation.
One problem I recall was tightening the lower intake manifold bolts--there are one or two which require a crows foot to use a torque wrench; I'm not sure how a crow's foot affects torque readings. I didn't have crow's foot sockets so for just those bolts I used a box end wrench and guessed the torque (I still feel guilty about that). My engine still runs fine several thousand miles later. Also while you are in there it is a good opportunity to replace things like the heater hoses and the o-ring on the oil pump drive. If the lower intake manifold shows pitting around the coolant ports you may be able to fill the cavities with hi-temperature metal epoxy and carefully smooth them flat. Good luck and have fun.
As for rotating the engine it doesn't really move that much, hardly worth the trouble. I couldn't figure how I was going to get to the back cylinders but I just started taking things off, once the intake manifolds are off there seems to be plenty of room to get the back head off. I can't recall rotating the engine for anything important, maybe I did, I could do most everything without the 3" rotation you mentioned. I can't recall when in the sequence I disconnected the exhaust or if that helped at all on the rotation.
One problem I recall was tightening the lower intake manifold bolts--there are one or two which require a crows foot to use a torque wrench; I'm not sure how a crow's foot affects torque readings. I didn't have crow's foot sockets so for just those bolts I used a box end wrench and guessed the torque (I still feel guilty about that). My engine still runs fine several thousand miles later. Also while you are in there it is a good opportunity to replace things like the heater hoses and the o-ring on the oil pump drive. If the lower intake manifold shows pitting around the coolant ports you may be able to fill the cavities with hi-temperature metal epoxy and carefully smooth them flat. Good luck and have fun.
June 17th, 2015, 11:25 AM
#3
CF Beginner
Thread Starter
Join Date: Jun 2015
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Thanks a lot for the reply. I really appreciate the tips. I worked on it a few hours this morning and made some nice progress. At least it's not overhead cam. Not looking forward the the exhast manifold part.
June 19th, 2015, 1:40 PM
#4
CF Beginner
Thread Starter
Join Date: Jun 2015
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Well finally got the heads off. Only snaped one bolt. Didn't break any tools. No cuts and only one hole in a tee shirt. Working at a slow pace. But not getting frustrated with the task at hand.
One of the pistons looks like it just came off the shelf , the other 5 have some carbon on them. Head gasket failed at one spot, and the intake manifold gasket at 2 places.
Just ordered some parts and going to take a break from this job while waiting for the parts to arrive.
Other than the Heater hose cluster , any other good advise at what I should fix while the heads are off. Not sure where this oil pump o ring is.
I curse every time I change the air filter on this van. Didn't curse this job so far. Hope I can keep the good attitude.
<!-- / message -->
One of the pistons looks like it just came off the shelf , the other 5 have some carbon on them. Head gasket failed at one spot, and the intake manifold gasket at 2 places.
Just ordered some parts and going to take a break from this job while waiting for the parts to arrive.
Other than the Heater hose cluster , any other good advise at what I should fix while the heads are off. Not sure where this oil pump o ring is.
I curse every time I change the air filter on this van. Didn't curse this job so far. Hope I can keep the good attitude.
<!-- / message -->
<!-- controls -->
June 20th, 2015, 1:00 PM
#5
CF Beginner
Join Date: Dec 2014
Location: Washington State
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
Oil pump drive o-ring
Go to google type in "gm 3.4L oil pump drive" and then select "images" and scroll down to see several photos of the drive, it's o-ring and location on the top of the block underneath where the throttle body is. It only takes one bolt to remove it's hold-down and is a common oil leak source on these engines. I got the new o-ring at the Chevy dealer to make sure it was an exact fit. Removal, install new o-ring and replace was a 10-15 minute job.
When fitting a lower intake manifold gasket whatever brand you chose I strongly recommend getting one with the metal disks/plates near the outer bolt holes; these are torque limiters to prevent over torquing which I guess is why this engine has such a notorious reputation for internal coolant leaks at the lower intake manifold coolant passages. If you go to google images and type in "3.4L failed lower intake manifold gasket" and go down about 5 rows you will see somebody's failed gasket--mine looked exactly like that with the rubber seal broken away from the plastic carrier. I believe the Fel Pro Perma-dry Plus has a bigger sealing ring, a metal frame instead of plastic and torque limiters (see images on first row of that last google image search mentioned).
The heads will probably need to be milled as they may have a few thousandths of an inch of warp in them and you don't want to do this job and blow another head gasket. Any decent automotive machine shop should be able to do it. BTW there is an updated torque sequence and torque amount on the heads, yet there are still the old torque values and sequence still out there so make sure you use the updated higher "angle" torques and the spiral from center out sequence and not the old values and sequence. I assume you are keeping the pushrods in order and know the exhausts are a different length than the intake.
I had two "steam cleaned" pistons on my engine. Congratulations and hope everything goes smoothly for you.
When fitting a lower intake manifold gasket whatever brand you chose I strongly recommend getting one with the metal disks/plates near the outer bolt holes; these are torque limiters to prevent over torquing which I guess is why this engine has such a notorious reputation for internal coolant leaks at the lower intake manifold coolant passages. If you go to google images and type in "3.4L failed lower intake manifold gasket" and go down about 5 rows you will see somebody's failed gasket--mine looked exactly like that with the rubber seal broken away from the plastic carrier. I believe the Fel Pro Perma-dry Plus has a bigger sealing ring, a metal frame instead of plastic and torque limiters (see images on first row of that last google image search mentioned).
The heads will probably need to be milled as they may have a few thousandths of an inch of warp in them and you don't want to do this job and blow another head gasket. Any decent automotive machine shop should be able to do it. BTW there is an updated torque sequence and torque amount on the heads, yet there are still the old torque values and sequence still out there so make sure you use the updated higher "angle" torques and the spiral from center out sequence and not the old values and sequence. I assume you are keeping the pushrods in order and know the exhausts are a different length than the intake.
I had two "steam cleaned" pistons on my engine. Congratulations and hope everything goes smoothly for you.
Last edited by ShortVenture; June 20th, 2015 at 1:12 PM.
June 24th, 2015, 7:52 PM
#6
CF Beginner
Thread Starter
Join Date: Jun 2015
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Hey , Thanks again for the tips. It is very helpful. Where can I find the updated torque specs ? I looked online and came up with 44 ft lbs, and then another 90 degree's. I need to search around for all the info. Still waiting on some parts. May try and get started on it this weekend.
June 25th, 2015, 10:54 PM
#7
CF Beginner
Join Date: Dec 2014
Location: Washington State
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
Now I'm confused
I tried to find what torque specs and sequence I used but I couldn't find where I wrote it down or else I didn't write it down. I think it was 44 lb-ft then 95 degrees but I am not sure. I used a slip of paper "instructions" that came in the Fel-Pro gasket set. I don't know what brand of gaskets you decided to go with, maybe they have instructions or an 800 technical help line. I did a quick google search "GM 3.4 L head torque" and there are all kinds of answers. Perhaps your local GM dealer service department will be a pal and tell you the latest torque specs and whether to use spiral or cross torque sequence, it sounds like it may have been changed a few times. Some places I saw had two different torque specs for older and higher torque for newer engines. Wish I could help more. Good luck.
I am not sure if this link will work (Federal-Mogul Resource Center - Torque Specification Look-up) but if it does this is from Fel Pro for a 1998 Silouette (for a 1998 it says 37 lb-ft then 90 degrees; then for fun I resubmitted a 2004 Chevy Venture and it said 44 lb-ft and 95 degrees): Federal-Mogul Resource Center - Torque Specifications
I am not sure if this link will work (Federal-Mogul Resource Center - Torque Specification Look-up) but if it does this is from Fel Pro for a 1998 Silouette (for a 1998 it says 37 lb-ft then 90 degrees; then for fun I resubmitted a 2004 Chevy Venture and it said 44 lb-ft and 95 degrees): Federal-Mogul Resource Center - Torque Specifications
Trending Topics
June 26th, 2015, 2:15 PM
#8
CF Beginner
Join Date: Dec 2014
Location: Washington State
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
From the Factory Service Manual 2nd Edition
For 1998 Venture, Tran Sport, & Silhouette page 6-9 (vol 3): Cylinder Head Bolt the book says 50 n-m (= 37 lb ft) + 90 degrees. On page 6-129 the torque sequence is the spiral pattern from the inside out:
Intake Manifold side
6 2 3 7
5 1 4 8
Exhaust
I assume you have a model year 1998? Good Luck.
Intake Manifold side
6 2 3 7
5 1 4 8
Exhaust
I assume you have a model year 1998? Good Luck.
July 3rd, 2015, 7:23 PM
#9
CF Beginner
Thread Starter
Join Date: Jun 2015
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Well finished it up this afternoon. Everything went very good. Started right up and just put 20 miles on it with no issue's. Hope to get a few more years out of it. Overall the job went a lot better than I thought it would.
The new head bolt set from fel-pro had a slip of paper with the recommended torque setting and sequence. It said 44 ft lb's and then 95 degree's. Doubt I was accurate enough to see any difference between 90 and 95 degree's.
I recently bought a Lisle spill free funnel. It really works great to refill the coolant system on this van. I highly recommend it.
Thanks again for the tip's. I did replace all the rubber coolant hoses under the hood. And the oil pump o-ring. Greg
The new head bolt set from fel-pro had a slip of paper with the recommended torque setting and sequence. It said 44 ft lb's and then 95 degree's. Doubt I was accurate enough to see any difference between 90 and 95 degree's.
I recently bought a Lisle spill free funnel. It really works great to refill the coolant system on this van. I highly recommend it.
Thanks again for the tip's. I did replace all the rubber coolant hoses under the hood. And the oil pump o-ring. Greg
July 4th, 2015, 1:58 PM
#10
CF Beginner
Join Date: Dec 2014
Location: Washington State
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
Congratulations
Glad to hear you got it all back together and running smoothly. I trust you did not get any antifreeze in your oil or you changed the oil as part of the job. From what I read the lower intake manifold (LIM) gasket is the weakest link in this engine so if it holds up you should have many miles to go. Which LIM gasket did you decide to go with? Again, Congratulations.
