98 Lumina Blown Head Gasket?

[sting8282bird]

I have a 98 Chevy Lumina 3.1L automatic 191k miles. I have been getting a P0401 (EGR low flow) code for a year and a half, and figured I had a vacuum leak. I checked all the lines and connections, replaced PCV, replaced some grommets, cleaned then replaced EGR valve (wasted $150), and couldn’t find the problem. I managed to pass emissions by clearing the code, but the problem got worse recently.

The car makes a whistling/whirring sound that changes with engine speed (and has for a while). The car has been losing coolant (no puddles) and has been overheating at low speeds (<20-25 mph). I was going to check for fan operation last night, but while I was warming up the car to see if the fan came on, it warmed up too fast. When I turned the car off, I heard a hissing/bubbling sound and smelled burning coolant. I popped the hood and looked around, and there was coolant bubbling at the point where the front head meets the block right behind the water pump. I couldn’t tell if coolant was bubbling out, or air was escaping. The only other things that are happening with this car are that it loses oil (1 quart every couple months), and it doesn’t start well when cold.

In reading all the posts, I’ve come to assume that the head gasket is toast. Would that leak to the outside of the engine like this? If it is the head gasket, are there other problems that could be found when replacing the gasket (I’ve read about warped intake plenum and lower intake manifold)? Also, how much would I expect to pay at a shop? Is there any correlation between the P0401 code and a blown head gasket? If I am way off, please let me know what the problem could be.

Thanks,
Scott

[maxwedge]

The cooling system needs to be pressure tested to pinpoint the leak, could be the lower intake gaskets which were very common. 401 has no effect on the leaks or overheating this is a seperate issue.

[Bearwulf]

As far as the 401 code, try cleaning the egr line all the way from the manifold to the valve base (pull loose from both ends). Probably fairly plugged with carbon.

[sting8282bird]

For the pressure test, is that a matter of hooking up a water hose, is that enough pressure. I know at least one place that is leaking. It appears that by replacing the head gasket and intake manifold gaskets, and cleaning the plenum and egr port that should handle those problems? Is the head gasket too much for a novice on this engine? Does this engine have overhead cams that i will have to remove the timing chain housing or do i just have to remove the plenum, lower intake manifolds, and heads?

[maxwedge]

There is a specific tool to pressure test the cooling system by putting pressure in the radiator. Due respect here, but by the tone of your questions and unless you have done this type of head gasket job before, I would look closely at what is involved, get a basic shop manual and see what's what.

[sting8282bird]

I will be following a Haynes manual i have if i fix it. What i'm trying to gauge is whether this is something i can fix (my grand am had overhead cams, and i would prefer not to take apart parts of the engine that i could easily screw up the timing), something i should pay to have fixed (what the cost might be), or sell the car for whatever i can get for it and buy a new one.

[inafogg]

like stated above system needs to be pressure tested if it turns out to be h/gasket
i'd think about 1k parts/labor

[zaac]

Check the spark plugs and if any are nice and clean then those cylinders are getting antifreeze in them. Is there lots of white smoke out the exhaust?

[sting8282bird]

I found the leak for sure when i took off the intake manifold, it was at the corner where the intake manifold, head, and block meet. the leak is to the outside of the engine, not to the cylinder (no white smoke). I'm going to replace the head gaskets since i'm this far into the job.

I trouble-shot my fan problem some more. the fans work when 12V is applied, but do not when the coolant gets hot, or when the A/C is turned on. I checked fuses and swapped relays for identical relays for the horn and ignition and both still work. When i unplug the coolant temperature sensor near the thermostat, the fans both come on. Does this sound like my temperature sensor/switch is bad? I replaced it a while back, so it may have been a dud. I tried to check the wiring by shorting the plug, and the fan didn't start when i put the jumper wire across it. the plug has 3 leads and i jumpered 3 times to be sure. When i tried this, the ignition was "On", but the engine was not running. Should the engine be running to perform this check?

I'm gonna try and clean out my EGR passages (both from the exhaust manifold and the inlet into the plenum). Any suggestions on how to clean the plenum out since theres no straight shot with a brush (pipe cleaner?)?

[kevinb70]

*bumped*

that egr might be set off by a bad cat, which by the way was probably clogged by leaking coolant from the LIM into your cylinders then out the exhaust... happened to me. I was also getting egr code... new egr didnt help one bit. Hows the power going uphill at 50mph+ ???

once i do a brake job for someone today, I'll be putting the lumina in my garage and tearing down for my 2nd LIM change - first replacement was that same crap plastic gasket as the original. Getting the metal one now its available. Probably tear the heads off to make sure cylinders are ok. sandblast, repaint, probably new lifters and springs.


overheating may be caused by dexcool sludge... is coolant clear?

[sting8282bird]

when i took the heads off, the dexcool sludge was blocking many of the passages (some looked like baked brownies). I've cleaned that out and am about to start putting it all back together, then flushing the entire system to try and get that stuff out. I'm going to clean the EGR line into the throttle body very well to see if that takes care of the P0401 code.

i'll check on the cat if it comes to it. is there a way to clean it?

The only thing after that is to figure out why the fans aren't working. i'm gonna replace the temperature sensor/switch. Also, there is another sensor that plugs in the front of the engine right in the middle (centered between the heads, but closer to the water pump). what is that sensor? I haven't really checked into it, but is that oil, coolant, or what?

[kevinb70]

if only we could seafoam the coolant passages

i prefer the Tomco Klean Screen egr gasket... has a screen to block the larger carbon chunks that might get into the egr and clog it or prevent it from closing all the way.

however... if you got a clogged cat then that might be causing your egr code ... i had a low egr flow or seomthing code when my cat was clogged, makes sense how the code appears when you think about it... skip over your egr code until you check the cat... i really think you are wasting your time thinking something is wrong with the egr/egr tube.

magnaflow has a direct fit cat, cost me like 150-160 (this year) at autozone (just checked and its about 200 now), check all the local parts places then check online for cheaper.

no, can't clean the cat ... but make sure its bad before u replace it. coolant will clog it, eventually. you can unbolt it from the collector, pop out the o2 sensor, see if it runs better. if you have a 0-5psi pressure gauge you can measure backpressure caused by the cat. bang it with a fist to see if it rattles, all else fails drill a hole on either end to visually inspect, think the pipe is too bent to see down it.


i think there is a engine coolant temperature sensor and a separate temperature switch for the fan....

temp sensor/switch might be so clogged with sludge it is too insulated to take a good temperature reading. i dont think you can always count on the A/C compressor to activate the efans, i think it's a pressure switch on the high side that is used to control efans.

i think efan cut-on temp is 220-230ish.

[sting8282bird]

thanks, i'll check all that when i finish putting it back together and let you know what i've found.

[sting8282bird]

Finished the head gasket job yesterday. seems to be running ok now. i still have to flush coolant and change oil, etc., but no leaks.

The P0401 code was due to an extremely clogged EGR passage to the air intake plenum (between egr and behind throttle body). when i first looked at it, i could spray carb cleaner in one side and it would just pool, but not travel through the passage. after about half an hour of scraping carbon rocks out of it with a pick and using a wire to "floss" the passage, it seems to be much cleaner and the code has gone away.

The last item on my list was the electric fans. i replaced the coolant temperature sensor, and the fans come on when i turn on A/C. I have not checked to see if they run with a warm temperature because it is running so much cooler now that the passages are clean that it takes a while to heat up.

thanks for all your help. I hope someone will at least find the P0401 code info useful!

[GreatGatsby]

@sting8282bird

I have a 98 Lumina, and I suspect the head gasket has a leak. Wild temperature swings, even after thermostat and radiator cap replacement. Radiator and water pump seem to be working fine.

Did you replace both the front and back head gaskets? I suspect my back one is bad, and I don't know how tough a job that is. I replaced my lower intake manifold gaskets and front head gasket in 2003.

Or, how much would I expect to pay the man to do it?