GM 3.4L V6 Overheating- headgasket?

[Nick R]

Okay so I have a lady friend from work, one that I'm pretty close to and will be among those joining me for trips coming up. I want to help her out. They have a 1998 Chevy Venture Van with 160k miles on it. They stopped driving it 9 months ago because it was overheating, and burning oil. Well she needs a car, and they still have it. So I stopped over today to take a look at it.

Well, after attempting to jump start it with my cruze, it would start running, and then almost immediately die again. Cause was the usual- simply out of gas. Filled it with a 2 gallon gas can, and sure enough it fired right up. It does smoke. It's a white smoke. It doesn't have any particular odor though, which confused me.

The engine ran fine, and the oil was black, but no sign of coolant. I know these engines are notorious for head gaskets, and LIM gaskets. But the coolant seems fine. It doesn't bubble, it doesn't smell funny, and the oil is basically coolant free. So I'm kind of at a loss here. We drove it around her neighborhood, and it has plenty of power, and it didn't seem to be overheating really. in fact, it seemed to stay really cold. Which rang a couple bells for me. First of all, neither she nor her parents know much about cars at all, and don't really know what's going on with this.The coolant was still full after sitting for 9 months, and didn't smell contaminated.

So what I'm wondering is, could it be as simple as a thermostat and/or water pump? It stopped smoking after running for 5 minutes or so. The oil again after shut down was coolant free, and it ran perfectly. So I'm struggling here. Anyone have any suggestions? I was thinking about doing a good tune up on it. Spark plugs, water pump, thermostat, oil change, power steering fluid change, air filter, PCV valve, and a new battery, new front pads. (this battery is completely shot. It starts fine when hooked up to my cruze, and once it's running it's fine. But shut it off and it's completely dead.

anyone with experience with these engines have any suggestions?

 

[Dakota1820]

Probably the intake . Just did my neighbors it was using oil and coolant but didn't overheat or smoke. But when we took it off you knew it was bad. That is probably the issue. You can fix it 3hours or less. Its a breeze really . Not hard at all.

 

[Nick R]

Originally Posted By: chevyboy14
Probably the intake . Just did my neighbors it was using oil and coolant but didn't overheat or smoke. But when we took it off you knew it was bad. That is probably the issue. You can fix it 3hours or less. Its a breeze really . Not hard at all.


I'll probably do that. Also, I forgot to mention, it didn't overheat, but at first it did get close. Then it suddenly cooled way off, and then it kind of stayed about 1/3 of the way up, but fluctuated a lot. That sounds like a stuck t-stat to me too.

 

[Dakota1820]

Retract last statement its harder in a van just because the lack of room. It could be a head to though. Pressure test?

 

[Dakota1820]

Hard to tell. Could be a stuck t stat but the using oil is the big hint for me. I know when my neighbors intake was bad it ran fine but used coolant and oil like crazy. But didn't smoke really and didn't run bad. 3.4 was kinda a turd lol. It had all of gms problems wrapped into one engine. Heads intake some did tick pretty bad

 

[Colt45ws]

Shine a light down on the transmission side of the engine, underneath the exhaust crossover and thermostat. There is a indented area of the engine. Look for liquid pooling and running down the front of the transmission. The ones with leaking LIMs seem to like to leak coolant out of the intake bolt near the thermostat and itll pool in that area.
I also like to look in the same area on the other side, under the PS pump. On that side, you can more clearly see the lower intake to engine interface. Look for RTV gooped at that interface. I also check for RTV on the sides of the valve covers, near the top at the "triangle" of the gasket where it seals to both the head and lower intake. If RTV is gooped all over the place, its likely someone was in the engine before.
I check this because Ive found many people dont remember or know what is done to their car when they take it in. You'd think spending several hundred to a thousand bucks or more would burn the problem into peoples brains, but it does not.

 

[crinkles]

do you have a date yet?

 

[demarpaint]

You can try pressure testing the cooling system to rule out a bad head gasket and other leaks quickly. If there are no leaks replacing a thermostat and flushing the cooling system is cheap insurance. I'd go with an OEM thermostat replacement. Get it together and drive it for a while and see. You might have to replace the water pump too. JMO

 

[NHGUY]

The 3.4...the overgrown sibling of the 2.8 (Citation),3.1 family.Had a 2.8 Camaro,made tons of ticking noises and little power.

 

[garageman402]

I've owned a 2000 Montana since it had 23K in 2000, and it didn't last 160K. Intake gasket leaks about every 60K, ticking noise turned out to be a #2 wrist pin which finally let go at 158.8K.

The first gasket set was replaced under warranty at 60K. Only clue was coolant level dropping, low coolant light came on. No sign of contamination in oil. By 136K, I was doing analysis, and glycol showed up. Not wanting to tear it down again, tried stop leak. Transmission was replaced and saw intake gasket sweating when engine was out, so replaced them. Also did lifters while it was off to try and solve a ticking noise.

By around 157K, we pulled the intake again, to replace lifters again still trying to solve the ticking noise. The gasket wasn't leaking, but was evident it was going to soon, the surface around the water passage was crimped. Even the new design gaskets are prone to leaking. A couple of push rods had wear marks where they were rubbing some intake manifold casting slag. Took a dremel to the intake, this solved the ticking except for one single tick, that was eventually it's demise............

This van is not easy to work on, I can't even get to the rear plugs, even with removing the upper mounts and pulling the engine forward, as GM says to do. I can't believe your (girl)friend's van hasn't been worked on before, having 160K. I have a friend who had a 2000 Malibu 3.4L with the same problem at 60K, he dumped it, not being a car person.

Good luck.

 

[The_Eric]

Originally Posted By: NHGUY
The 3.4...the overgrown sibling of the 2.8 (Citation),3.1 family.Had a 2.8 Camaro,made tons of ticking noises and little power.


Actually, the 3.1 and 3.4 ran tons better than the old 2.8, with the 3.4 running much better than the 3.1. In the right platform, such as a Grand Am GT, they git right along...


Originally Posted By: garageman402
I've owned a 2000 Montana since it had 23K in 2000, and it didn't last 160K. Intake gasket leaks about every 60K, ticking noise turned out to be a #2 wrist pin which finally let go at 158.8K.

The first gasket set was replaced under warranty at 60K. Only clue was coolant level dropping, low coolant light came on. No sign of contamination in oil. By 136K, I was doing analysis, and glycol showed up. Not wanting to tear it down again, tried stop leak. Transmission was replaced and saw intake gasket sweating when engine was out, so replaced them. Also did lifters while it was off to try and solve a ticking noise.

By around 157K, we pulled the intake again, to replace lifters again still trying to solve the ticking noise. The gasket wasn't leaking, but was evident it was going to soon, the surface around the water passage was crimped. Even the new design gaskets are prone to leaking. A couple of push rods had wear marks where they were rubbing some intake manifold casting slag. Took a dremel to the intake, this solved the ticking except for one single tick, that was eventually it's demise............

This van is not easy to work on, I can't even get to the rear plugs, even with removing the upper mounts and pulling the engine forward, as GM says to do. I can't believe your (girl)friend's van hasn't been worked on before, having 160K. I have a friend who had a 2000 Malibu 3.4L with the same problem at 60K, he dumped it, not being a car person.

Good luck.


They're tough to work on, but not impossible. I've had the displeasure of doing several now and am to the point where head or intake work isn't much worse than in a car. It sounds like your gaskets were replaced with the plastic framed set a few times. Somewhere along the line, Fel-Pro came out with steel frame gaskets that really upped their durability (Nick, take note here).


Nick, I applaud your good intentions, but are you sure you're ready to tackle an intake job and get it right? Also, in your list of tune up items, you were missing a fuel filter. Make sure to include that and a bottle of Techron cleaner.

 

[sciphi]

Those vans will keep on running for forever, even with lots of problems. Keep the coolant and oil topped up, and drive it until it rots away as they are very prone to doing. Not worth new gaskets and a tuneup at 160k miles unless the body and interior are in decent shape. I know two of those vans that are still ticking with 150k+ miles on them, both very indifferently maintained. Both will be dumped at the first sign of major work like new gaskets.

I'd tell them to keep a gallon of coolant and a few quarts of cheap oil on hand and check it every tank of gas if it's less than mint condition.

 

[SLCraig]

Originally Posted By: Nick R
Originally Posted By: chevyboy14
Probably the intake . Just did my neighbors it was using oil and coolant but didn't overheat or smoke. But when we took it off you knew it was bad. That is probably the issue. You can fix it 3hours or less. Its a breeze really . Not hard at all.


I'll probably do that. Also, I forgot to mention, it didn't overheat, but at first it did get close. Then it suddenly cooled way off, and then it kind of stayed about 1/3 of the way up, but fluctuated a lot. That sounds like a stuck t-stat to me too.


It probably cooled way off because there was no coolant touching the temp sensor.. My guess is the coolant was topped off not long before it was parked and that is why it looks fine. Give it a while and it would probably be out of coolant. Don't be fooled by a "low" readout on the gauge if coolant problems are in question.

 

[GMBoy]

Originally Posted By: demarpaint
You can try pressure testing the cooling system to rule out a bad head gasket and other leaks quickly. If there are no leaks replacing a thermostat and flushing the cooling system is cheap insurance. I'd go with an OEM thermostat replacement. Get it together and drive it for a while and see. You might have to replace the water pump too. JMO



Good advice here.

 

[bmod305]

I have done about 3 intake jobs on 3.4's in GM vans-once on mine and a couple of friends. About a six hour job. Buy the updated Permadry intake set from FelPro. GM revised the intake bolt torque so make sure you get the new info. Let me know if you have any questions.

Thanks,

Dave

 

[garageman402]

Thanks bmod305 and The Eric for advice on the gaskets. Do you think a GM service replacement (rebuilt) engine would have those gaskets? Or would it have the original OEM Delco ones? I did get a new engine because the van is in very good shape, inside and out it looks new. New headlight capsules really make it look new again.

Sorry Nick, didn't mean to hijack, just wanted to say thanks.......

 

[Colt45ws]

I think GM is still using the plastic gaskets. I could be wrong but they didnt bother to update the 3.4L design to the metal ones like they did with the 3.8L. They did this because they were ending the 3.4L and transitioning over to the 3.5L.

My advise is to check it and double check it for a head gasket problem. I did the intake gaskets on my grandparents Montana then 2000 miles later I was back into it to do the heads.
btw, I never saw coolant in the oil with theirs. I did a used oil analysis and caught it through that. It had 0.5% coolant. Virtually nothing.

 

[The_Eric]

Originally Posted By: garageman402
Thanks bmod305 and The Eric for advice on the gaskets. Do you think a GM service replacement (rebuilt) engine would have those gaskets? Or would it have the original OEM Delco ones? I did get a new engine because the van is in very good shape, inside and out it looks new. New headlight capsules really make it look new again.

Sorry Nick, didn't mean to hijack, just wanted to say thanks.......


That's a good question. If it came with the intake already installed then I think it would have the plastic framed gaskets. If it came as the typical long block does, then you or the mechanic would have to install gaskets/intake. Sometimes they're supplied with the engine, sometimes not. That is something you may be able to figure out by looking through your paper work.

 

[Hannibal]

Originally Posted By: Colt45ws
My advise is to check it and double check it for a head gasket problem. I did the intake gaskets on my grandparents Montana then 2000 miles later I was back into it to do the heads.
btw, I never saw coolant in the oil with theirs. I did a used oil analysis and caught it through that. It had 0.5% coolant. Virtually nothing.


+1

I had a 2005 Equinox that had about 65k on it. One day it starts overheating. My father in law and I did all sorts of fixes to it because we couldn't find coolant in the oil. The coolant reservoir would hold coolant as well.

One night, a few days after changing the t-stat, water pump, etc. It started billowing white smoke out the exhaust. Next day it went to the shop. Sure as anything...head gasket was blown. Another day or two I got a call saying that the heads were warped as well!

That's the only car I've ever traded in that I didn't have a moments hesitation. Complete trash...

GM told me to pound sand too after I called them up. I chased them a few times because I didn't feel it was reasonable that a head gasket should blow at 65k. We had a Honda Accord at the time too that had 85k on it and Honda replaced the battery in it for free after we had some problems with it. We were way out of warranty on that one.

 

[tmorris1]

Originally Posted By: Nick R
Originally Posted By: chevyboy14
Probably the intake . Just did my neighbors it was using oil and coolant but didn't overheat or smoke. But when we took it off you knew it was bad. That is probably the issue. You can fix it 3hours or less. Its a breeze really . Not hard at all.


I'll probably do that. Also, I forgot to mention, it didn't overheat, but at first it did get close. Then it suddenly cooled way off, and then it kind of stayed about 1/3 of the way up, but fluctuated a lot. That sounds like a stuck t-stat to me too.

I have a 98 Montana and I will almost guarantee you this is the head gasket. This is the exact same thing that mine did. It smoked a little and the temp gauge fluctuated up and down a lot. After a while of this it started overheating and you could see bubbles in the coolant overflow. Fixed it at about 155,000 and now have over 180,000 on it and it runs great. Fel-Pro problem solver gaskets were used. The mechanic said he has never had one of the new Fel-Pros fail yet.