gen 2 and gen 3 3.8l
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ls1mike
$50 Site Donor 2024
The Series II can have the problem. The Series III is 04 and up. The Series III has the metal framed intake gasket and should not have the problem unless it was neglected.
What are looking at exactly? N/A or Supercharged? Are you handy with a wrench? The intake gaskets on these are easy.
What are looking at exactly? N/A or Supercharged? Are you handy with a wrench? The intake gaskets on these are easy.
+1 what mike said. Only thing I want to add is the series 2 will still have plastic upper intake manifold failure regardless of lower intake gasket material. I have not seen the Dorman UIM fail if torqued correctly and the EGR stove installed per instructed. Series 3 uses an aluminum UIM that I haven't seen fail.
Originally Posted By: beast3300
I have not seen the Dorman UIM fail if torqued correctly and the EGR stove installed per instructed. Series 3 uses an aluminum UIM that I haven't seen fail.
Hijacking thread somewhat...I've used the dorman UIM manifold but the bolts seem to loosen/gasket goes flat and leaks. I've replaced the upper intake gasket 3 times and the UIM 2x. 1st time as a precaution and the second time I noticed that the plastic manifold was warped when replacing the gasket. I just recently tightened the bolts because it was weeping antifreeze. This is slightly irritating because I followed instructions down to every detail. Looking at my notes it seems that the UIM gasket leaks occur after about 10k on average with the last replacement done around 25k but it has leaked.
I replaced the Lower intake manifold gaskets with the aluminum gaskets and and it has been perfect for the last 45k. I'm wondering what I've did wrong concerning the UIM gaskets to constantly have problems but zero issues with the lower intake gaskets.
I have not seen the Dorman UIM fail if torqued correctly and the EGR stove installed per instructed. Series 3 uses an aluminum UIM that I haven't seen fail.
Hijacking thread somewhat...I've used the dorman UIM manifold but the bolts seem to loosen/gasket goes flat and leaks. I've replaced the upper intake gasket 3 times and the UIM 2x. 1st time as a precaution and the second time I noticed that the plastic manifold was warped when replacing the gasket. I just recently tightened the bolts because it was weeping antifreeze. This is slightly irritating because I followed instructions down to every detail. Looking at my notes it seems that the UIM gasket leaks occur after about 10k on average with the last replacement done around 25k but it has leaked.
I replaced the Lower intake manifold gaskets with the aluminum gaskets and and it has been perfect for the last 45k. I'm wondering what I've did wrong concerning the UIM gaskets to constantly have problems but zero issues with the lower intake gaskets.
ls1mike
$50 Site Donor 2024
That is odd as I have never had that problem. Have you replaced the fasteners? Is the lower plenum surface warped?
When I did mine on my 98 Bonneville I updated everything and never had the problem again.
When I did mine on my 98 Bonneville I updated everything and never had the problem again.
I'm not sure either. The only thing I do extra is check the final 89 inch lbs after letting it sit a while because the gasket will settle. Once all the bolts click click then I resume installed stuff.
Edit: I just realized something. You have your thermostat installed with the o-ring AND paper gasket? Only 99 and newer are OK without the paper gasket.
Edit: I just realized something. You have your thermostat installed with the o-ring AND paper gasket? Only 99 and newer are OK without the paper gasket.
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Originally Posted By: ls1mike
That is odd as I have never had that problem. Have you replaced the fasteners? Is the lower plenum surface warped?
When I did mine on my 98 Bonneville I updated everything and never had the problem again.
What fasteners? are you referring to? I'm stumped myself as it is a straight forward process. I never thought of the lower intake manifold to surface being warped. Before I changed the UIM the first time it only had a slight leak. I had owned the car for about 50k miles at the point. The car has 207k miles on it and is close to 20 years old and doesn't get drove much now so I think I will just let it become an annoyance at this point. But I really wonder if I did something wrong or it's just the luck of the draw.
Also yes I do have a gasket on the thermostat housing along with sealant. No leaks there. I think there is a slight water pump leak also that has been going on for years but I can't 100% confirm it. So it hard for me to gauge coolant loss due to the intake gaskets but it's not dramatic.
That is odd as I have never had that problem. Have you replaced the fasteners? Is the lower plenum surface warped?
When I did mine on my 98 Bonneville I updated everything and never had the problem again.
What fasteners? are you referring to? I'm stumped myself as it is a straight forward process. I never thought of the lower intake manifold to surface being warped. Before I changed the UIM the first time it only had a slight leak. I had owned the car for about 50k miles at the point. The car has 207k miles on it and is close to 20 years old and doesn't get drove much now so I think I will just let it become an annoyance at this point. But I really wonder if I did something wrong or it's just the luck of the draw.
Also yes I do have a gasket on the thermostat housing along with sealant. No leaks there. I think there is a slight water pump leak also that has been going on for years but I can't 100% confirm it. So it hard for me to gauge coolant loss due to the intake gaskets but it's not dramatic.
ls1mike
$50 Site Donor 2024
Fasteners as in bolts.
No I didn't change the fasteners. I thought that since they're low torque bolts, that the didn't need to be changed. Do the intake manifold bolts stretch? Or is it good practice to change them out?
Ram_man, what particular cars with the 3800 are you looking at?
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ls1mike
$50 Site Donor 2024
Originally Posted By: ram_man
Ive looked at 2 3.8 cars and both leaked. one had a coolant leak and on had oil puddled in the back beteween valve cover and valve cover. Not sure if the intake ca or will usually leak oil externally though.
That was valve covers. Easy Peasy. The intake won't usually leak oil externally.
Ive looked at 2 3.8 cars and both leaked. one had a coolant leak and on had oil puddled in the back beteween valve cover and valve cover. Not sure if the intake ca or will usually leak oil externally though.
That was valve covers. Easy Peasy. The intake won't usually leak oil externally.
ls1mike
$50 Site Donor 2024
Originally Posted By: DC44
No I didn't change the fasteners. I thought that since they're low torque bolts, that the didn't need to be changed. Do the intake manifold bolts stretch? Or is it good practice to change them out?
You don't, but I did to be safe. I usually put a little RTV on them.
No I didn't change the fasteners. I thought that since they're low torque bolts, that the didn't need to be changed. Do the intake manifold bolts stretch? Or is it good practice to change them out?
You don't, but I did to be safe. I usually put a little RTV on them.
I used loctite but it doesn't seem to work. I'll probably put rtv sealant on the bolts in the future when I get around to it. The car is getting close to the end of its days age wise.
yes it's pretty common but it's stupid easy to change the front. I'm not sure how hard it is to change the back on W body 3800 as it has a smaller area to work in than my H body 3800. Also on the back valve cover I had to remove the alternator bracket...but it may be different on newer 3800's. I'm not really sure though.
If it is a grand prix there would be other things I would worry about such as pass-lock if its 2003 and older, or trans solenoid depending on the mileage. Although it doesn't seem to be as big of a problem as it is magnified on the internet in real life from my experience.
The intake problem is real and will happen if you don't take care of it. If you decide to get a 3800 engine car that should be the first order of business if the can't prove that the changed it recently.
If it is a grand prix there would be other things I would worry about such as pass-lock if its 2003 and older, or trans solenoid depending on the mileage. Although it doesn't seem to be as big of a problem as it is magnified on the internet in real life from my experience.
The intake problem is real and will happen if you don't take care of it. If you decide to get a 3800 engine car that should be the first order of business if the can't prove that the changed it recently.
Originally Posted By: DC44
yes it's pretty common but it's stupid easy to change the front. I'm not sure how hard it is to change the back on W body 3800 as it has a smaller area to work in than my H body 3800. Also on the back valve cover I had to remove the alternator bracket...but it may be different on newer 3800's. I'm not really sure though.
If it is a grand prix there would be other things I would worry about such as pass-lock if its 2003 and older, or trans solenoid depending on the mileage. Although it doesn't seem to be as big of a problem as it is magnified on the internet in real life from my experience.
The intake problem is real and will happen if you don't take care of it. If you decide to get a 3800 engine car that should be the first order of business if the can't prove that the changed it recently.
so even if its good I should replace it?
yes it's pretty common but it's stupid easy to change the front. I'm not sure how hard it is to change the back on W body 3800 as it has a smaller area to work in than my H body 3800. Also on the back valve cover I had to remove the alternator bracket...but it may be different on newer 3800's. I'm not really sure though.
If it is a grand prix there would be other things I would worry about such as pass-lock if its 2003 and older, or trans solenoid depending on the mileage. Although it doesn't seem to be as big of a problem as it is magnified on the internet in real life from my experience.
The intake problem is real and will happen if you don't take care of it. If you decide to get a 3800 engine car that should be the first order of business if the can't prove that the changed it recently.
so even if its good I should replace it?
Unless the can give you the mileage at which they replaced it, then yes.It's a peace of mind issue.You can't tell from the outside all the time. The gasket usually starts to leak but the egr burning through the upper intake manifold is the real issue to worry about and this will not show from the outside if the gasket is good. I would say you have around 60-100k before it burns through. The newer 3800 had a smaller stove pipe but it's still effected by the issue.This will hydro lock the engine and possible if it leaks internal for a long period of time and mixes with the oil then you could end up spinning a bearing.I think the bearing issue has more to do with not changing the lower intake manifold because the leak slowly and right into the lifter valley. I've seen this happen at least three times and I tried to tell people about the issue before it happened to them but as long as a car cranks and sounds like it is running good they don't bother.
There's a stamp on the intake manifold that tells you what year it was manufactured so that will give you a good range. My last one was made in 2007 or 2010, I think, but I installed it in 2012
There's a stamp on the intake manifold that tells you what year it was manufactured so that will give you a good range. My last one was made in 2007 or 2010, I think, but I installed it in 2012
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