Should I replace the head gaskets when I replace the lower intake gasket?


J-Ri
01-15-2012, 04:45 AM
2001 Impala 3.4 L

I bought the car from a customer, it came in with a number of issues, and he decided not to put the money into the car, so I got it pretty cheap. The biggest problem is the lower intake gasket leaking coolant (appears to be external only at this point). The car has 195,000 miles on it, almost all highway from 70,000 miles when he bought it. It's been maintained well, and he's always had the work done by us, so I have all the maintenance/repair records and I know the work was actually done and was done right. Surprisingly, in that 125,000 miles, the intake gasket hasn't been done. I'm also fairly sure it's never overheated, he said it's never overheated (the reason he brought it it was the thermostat is stuck open and he had very little heat). He has been "topping off" the coolant, but he indicated that he never let the reservoir get empty (I heard that through the service writer, so I'm not entirely sure. I'll ask him myself when I pick the car up later today. Anyway, it's a very nice car for the age and miles (middle-age guy driving it on business trips). At this point I plan on driving it while I build-up the engine in my Cavalier (and probably take a few months to polish the supercharger, intake manifold, and fuel rail to a mirror shine to match the valve cover). After that, I may sell it, but I do really like these cars, and I may keep it for rainy weather and snow. Plus it would be nice not to have to drive my big ol' 8MPG truck if/when I break my Cavalier at the track. So I may own the car for a few months, or until it rusts apart.

How often do the head gaskets fail on these? I've done, literally, thousands of lower intakes on these. The shop I work at doesn't do head gaskets (just a rule, doesn't matter how simple the job is), but I'd say 1 in 100 cars that I do the lower intake gasket on comes back still overheating and I send it somewhere else for them to do the head gaskets. It also seems like the only ones with bad head gaskets are the ones that were extremely overheated repeatedly. Given the poor communication (to put it nicely) between the service writers and the technicians, there could be a significantly higher number that come back, but the service writers just tell the customer to go somewhere else because it has to be a bad head gasket. It's also possible that if a car has been overheating every day for 20 minutes on the highway for a year and the customer's been adding coolant, they just tell us "check coolant leak". I'd love some input from technicians that do both jobs and are given a clear picture of what the problem is (just coolant loss, or overheating)

On one hand, the intake gasket is pretty cheap and easy, but if I can avoid doing the head gaskets 10,000 miles later (2-3 months for me), I'd like to do the head gaskets now. But I really don't want to drill out broken exhaust manifold bolts or have the extra cost of the head gaskets and probably having the heads planed. The upside here is that I'm currently starting my own shop with a friend, and I have a fully-equipped shop that I can use whenever I want, so it's not the end of the world if I do have to do the head gaskets soon. The downside is that I'm working 2 full time physically intensive jobs until we get enough customers that I can quit the hell-hole I work at now, and I'm always tired, and never want to work on my own cars. So if I can do a 4 hour job and have it last for 6 months or more, I wont mind doing the head gaskets then because I'll almost certainly only be working at my shop. We've been growing so fast, I may not be "working for the man" more than a couple months. I just don't have the experience to fully judge for myself what I should do, and I appreciate any input.

Thanks,
Jason

luvmy02impala
01-16-2012, 09:58 AM
Hello,

I had an 02 Impala with a 3.4L engine. I bought the car at 49k miles and put 3 intake manifold gaskets on it. 55k, 110k and 154k. 2 months after replacing the intake manifold a 3rd time, the car caught fire and burned up. I am not saying that was the cause (neither did my insurance company investigation), but the recall on the 3.8L (intake manifold gasket) was for possible fire (why my insurance company decided to do a forensic investigation (and since i replaced it 3x).

There was a class action lawsuit against GM for the 3.4L because they claimed the trouble was only on the 3.8L.

The trouble I had each time, was the coolant (dex-cool) was leaking into the block mixing with oil. The coolant level would decrease and contaminate my oil. I had no notice this was happening until the low engine coolant light came on each time. Then i would check the oil and I would see the slimy mixture. I had regular oil changes, but they never really picked up the mixing, maybe because a slow gasket failure.

I would suggest to check the oil and see if it mixed with coolant. Plus, you start to hear chatter from the valves because the coolant is messing with the lubrication of the oil. Luckily there was no engine damage from my issues prior to each fix. However, long term, I will never know if I needed a 4th intake manifold gasket.

rkvons
01-16-2012, 01:52 PM
The intakes fail because of a defective intake gasket when the engine was manufactured. The head gaskets may fail from the engine overheating do to the intake gaskets, but they were not defective from the beginning. I would just do the intake and forget the heads. I have a '98 Monte Carlo with a 3.1 with 183K on the engine and it has never had its intake gasket replaced either. I plan on doing that this summer but will not be doing the head gaskets unless they fail. Just my :2cents:

luvmy02impala
01-17-2012, 08:09 AM
I forgot to mention, I had not replaced the head gaskets at anytime the intake manifold gaskets were changed. Only had the crankcase and cooling system flushed from contaminants.

j cAT
01-17-2012, 10:44 AM
with the mileage on this vehicle it is at the end of its life cycle. I would do the intake gaskets and check for any other leaks.

If the head gasket is bad the compression will show it and coolant in the oil as well.

if coolant is in the oil the engine is damaged as well as other items like O2 sensors cat converter ...

fuel prices are going up. 5.oo/GAL by june.

Tech II
01-17-2012, 04:05 PM
"but the recall on the 3.8L (intake manifold gasket) was for possible fire (why my insurance company decided to do a forensic investigation (and since i replaced it 3x)."

There was no recall for the intake manifold gasket on the 3.8....there was a recall for the front valve cover gasket, that might cause a fire.....

j cAT
01-17-2012, 07:13 PM
"but the recall on the 3.8L (intake manifold gasket) was for possible fire (why my insurance company decided to do a forensic investigation (and since i replaced it 3x)."

There was no recall for the intake manifold gasket on the 3.8....there was a recall for the front valve cover gasket, that might cause a fire.....

my guess the insurance company did investigate this to see if he did something improper that caused the fire.

they investigate to get out of paying any loss.

J-Ri
01-18-2012, 04:22 AM
with the mileage on this vehicle it is at the end of its life cycle..

Nah, I've seen these go to 300k and still running OK, the bodies on the cars were just so rusty we couldn't lift them on a hoist... and this one's been taken care of, not some highschooler's car. Also very little rust for something that's been in Iowa and Illinois it's whole life.


I asked the previous owner myself, he said it has never overheated and he had no reason to lie (and doesn't seem the type to do so), as cheap as I got the car there wasn't any bargaining room, especially with the 4 brand new tires (I really just paid a few hundred over the value of the tires and the scrap metal price of the car). I'd already handed him the check when I asked, too. I have checked compression, cyl leakdown, and did a combustion gas test as well, all were good, so I won't be doing the head gaskets.

Thanks for the input everyone, I suspected that overheating was the primary cause of the head gaskets going, but really wasn't sure it was the only cause (not saying it's the ONLY cause, but definitely seems to be the largest contributor)... that's what does it on most engines, but I found such a high number of head gasket failures on these engines on Identifix that I just wanted to see.

j cAT
01-18-2012, 08:02 AM
Nah, I've seen these go to 300k and still running OK, the bodies on the cars were just so rusty we couldn't lift them on a hoist... and this one's been taken care of, not some highschooler's car. Also very little rust for something that's been in Iowa and Illinois it's whole life



well that is what I was refering to. where I live the age and mileage 200,ooo would be a great amount of life in the rust belt on a vehicle stored outside and used daily.

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