3800 Series II 'faults'
Question:
"Tony" wrote > Correct me if I’m wrong, but won’t changing the coolant temp via the > thermostat screw with the computer? Won’t it make it think the car > needs to run rich, that it hasn’t wamed up completely? Wouldn’t that > screw with the O2 sensor/cat eventually?
Yeah…on some vehicles, the computer will set a code if it sees the coolant temperature persistently too low. We see this when you have a thermostat that is stuck open. Most modern engines are designed to run at a minimum of 195. Most electric cooling fans don’t come on until quite a ways past 195. Ian
Response:
That’s what I thought. The reason is I saw this first hand with my Stepfather. He replaced an ‘85 GMC 350 with a ‘94 Vortec (or something close to that, it’s hard to tell I am 2500 miles away going on 3rd hand info). They noticed it was "running hot all the time" so they replaced the thermostat with a 180. Then the truck would run rough and had a hard time warming up in the AM. I always thought they should go back to the 195, but I don’t think they even knew it was a 195, they just figured it was going bad and replaced it with what they are used to using. THey live in AZ so "running hot" in the summer is kind of subjective (until the steam comes out 
). Thanks Ian Tony – Hide quoted text — Show quoted text – >"Tony" wrote > Correct me if I’m wrong, but won’t changing the coolant temp via the > thermostat screw with the computer? Won’t it make it think the car > needs to run rich, that it hasn’t wamed up completely? Wouldn’t that > screw with the O2 sensor/cat eventually? >Yeah…on some vehicles, the computer will set a code if it >sees the coolant temperature persistently too low. We see >this when you have a thermostat that is stuck open. Most modern >engines are designed to run at a minimum of 195. Most electric >cooling fans don’t come on until quite a ways past 195. >Ian
Response:
– Hide quoted text — Show quoted text – >Interesting…but incorrect when it comes to the thermostat. >Lower coolant temperature will have no effect on the intake >manifold warping or not….as the problem is not coolant >temperature…but the temperature of the hot EGR gases >that are piped up "through" the plastic manifold from the >lower aluminum manifold. >You shouldn’t run a 180 degree thermostat on any modern >GM engine that I know of. Unless that engine specifically >calls for a 180. If the cooling system can’t keep the >temperature at 195…it won’t be able to keep the temperature >at 180. >Ian
I agree and have heard that alot, not to fuck with the 195 thermostat if that’s what it had. Using the same logic, if going from 195 to 180 is good, then wouldn’t going to 160 be better? Maybe for a ‘57 Bel-Air, but not for a ‘99 Regal. Correct me if I’m wrong, but won’t changing the coolant temp via the thermostat screw with the computer? Won’t it make it think the car needs to run rich, that it hasn’t wamed up completely? Wouldn’t that screw with the O2 sensor/cat eventually? Tony
Response:
Replace the 195 degree stat with 180 degree stat. Install an aftermarket tranny cooler like a Hayden 404. This will help extend the life of the plastic intake manifold. Spanky
– Hide quoted text — Show quoted text -> I have a 99 Regal LS w/ about 69K miles. I have heard of some ‘moderate to > major flaws’ with the 3800 Series II engine. Could someone please post > again what those are? > I guess that the only major design flaw it currently has is the plastic > upper intake manifold. I was "presented" with this issue last week on > my ‘02 Bonneville with just over 17000mls. :^( > Perhaps the only fix for it is to bring some aluminum manifolds from > Australia in the hope that they fit it…
Response:
> Replace the 195 degree stat with 180 degree stat. Install an aftermarket > tranny cooler like a Hayden 404. This will help extend the life of the > plastic intake manifold.
These are interesting suggestions. I get the lower engine temperature to spare the intake manifold, but what would the tranny cooler have to do with it? Thanks.
Response:
Does anyone think that some company would make an aftermarket all aluminum fix for it?
– Hide quoted text — Show quoted text -> Replace the 195 degree stat with 180 degree stat. Install an aftermarket > tranny cooler like a Hayden 404. This will help extend the life of the > plastic intake manifold. > These are interesting suggestions. I get the lower engine temperature > to spare the intake manifold, but what would the tranny cooler have to > do with it? > Thanks.
Response:
"Neo" wrote > These are interesting suggestions. I get the lower engine temperature > to spare the intake manifold, but what would the tranny cooler have to > do with it?
Interesting…but incorrect when it comes to the thermostat. Lower coolant temperature will have no effect on the intake manifold warping or not….as the problem is not coolant temperature…but the temperature of the hot EGR gases that are piped up "through" the plastic manifold from the lower aluminum manifold. You shouldn’t run a 180 degree thermostat on any modern GM engine that I know of. Unless that engine specifically calls for a 180. If the cooling system can’t keep the temperature at 195…it won’t be able to keep the temperature at 180. Ian
Response:
> I have a 99 Regal LS w/ about 69K miles. I have heard of some ‘moderate to > major flaws’ with the 3800 Series II engine. Could someone please post > again what those are?
I guess that the only major design flaw it currently has is the plastic upper intake manifold. I was "presented" with this issue last week on my ‘02 Bonneville with just over 17000mls. :^( Perhaps the only fix for it is to bring some aluminum manifolds from Australia in the hope that they fit it…
Response:
Looks like you work for a GM garage. I have noticed the intake on my 2000 S-10 is plastic also (2.2L engine) Is that why I hear the air rushing in, it sounds like filling a tire when the air compressor is located somewhere else so you don’t hear the noise from it, just that air rushing in.
– Hide quoted text — Show quoted text -> "Michael Sovitzky" wrote > I have a 99 Regal LS w/ about 69K miles. I have heard of some ‘moderate > to > major flaws’ with the 3800 Series II engine. Could someone please post > again what those are? > Sure, I’ll even go into some detail here. > Probably the most common problem that we see is > the warping/leaking of the upper intake plenum. It’s a > plastic upper intake plenum that sits on top of the lower > aluminum intake manifold. You can either get some > external coolant leaking like this: > http://www3.telus.net/public/ianrmac/Images/3800/380015%20(11).JPG > you can see the dried coolant pooling close to the thermostat housing, > what you can’t see is the other side of the manifold where it’s pouring > down the back of the bell housing. > Or you get a bad enough leak that it leaks internally and fills up > the inside of the lower intake, like this: > http://www3.telus.net/public/ianrmac/Images/3800/38001.JPG > nasty, eh? When they are this bad, they often hydrolock the > engine as the coolant starts to flow into the cylinders. What’s the > cause? This EGR pipe sticking out of the lower intake manifold: > http://www3.telus.net/public/ianrmac/Images/38002leaks.JPG > Here is a picture of the old and new manifold designs end to > end so you can see the smaller EGR pipe in the newer design. > http://www3.telus.net/public/ianrmac/Images/3800/3800intake.JPG > http://www3.telus.net/public/ianrmac/Images/3800/3800intak1.JPG > The old style EGR pipe overheats the inside of the upper intake > plenum and warps/damages it. > http://www3.telus.net/public/ianrmac/Images/3800/380015%20(16).JPG > Anyway, that’s one problem…I’ll post another one with details on > the other problem, (rear main housing gasket) > Ian
Response:
I have a 99 Regal LS w/ about 69K miles. I have heard of some ‘moderate to major flaws’ with the 3800 Series II engine. Could someone please post again what those are? And, based on my model year and the # of miles I have, is there anything I can replace or do to alleviate the design flaws? Thank you for your help. Michael
Response:
"Michael Sovitzky" wrote > I have a 99 Regal LS w/ about 69K miles. I have heard of some ‘moderate to > major flaws’ with the 3800 Series II engine. Could someone please post > again what those are?
Sure, I’ll even go into some detail here. Probably the most common problem that we see is the warping/leaking of the upper intake plenum. It’s a plastic upper intake plenum that sits on top of the lower aluminum intake manifold. You can either get some external coolant leaking like this: http://www3.telus.net/public/ianrmac/Images/3800/380015%20(11).JPG you can see the dried coolant pooling close to the thermostat housing, what you can’t see is the other side of the manifold where it’s pouring down the back of the bell housing. Or you get a bad enough leak that it leaks internally and fills up the inside of the lower intake, like this: http://www3.telus.net/public/ianrmac/Images/3800/38001.JPG nasty, eh? When they are this bad, they often hydrolock the engine as the coolant starts to flow into the cylinders. What’s the cause? This EGR pipe sticking out of the lower intake manifold: http://www3.telus.net/public/ianrmac/Images/38002leaks.JPG Here is a picture of the old and new manifold designs end to end so you can see the smaller EGR pipe in the newer design. http://www3.telus.net/public/ianrmac/Images/3800/3800intake.JPG http://www3.telus.net/public/ianrmac/Images/3800/3800intak1.JPG The old style EGR pipe overheats the inside of the upper intake plenum and warps/damages it. http://www3.telus.net/public/ianrmac/Images/3800/380015%20(16).JPG Anyway, that’s one problem…I’ll post another one with details on the other problem, (rear main housing gasket) Ian
