Where would my coolant go?

[pinkfloyd4ever]

92 Chevy C/K V6 A/C but I don't use it. In the last 6 weeks I have had to put in a full bottle of coolant. I don't see any obvious source of a leak, no puddles on ground or on hoses.

I drained and replaced the oil and it seemed normal.

Could it just be a slow drip only when I am driving? My temp gauge never alarms or anything.

[Jeremy airjer W]

The usual culprits are the intake gaskets and water pumps. If your not noticing it than it is probably only leaking when its hot. Look in the corner if the intake gasket where it meets the head on the front of the engine. If its leaking it will usually leave a trail.

There are three options, Wait for it to get worse, Pressure check the cooling system (both hot, cold, engine running, engine off), or add die to the cooling sytem which will make the leak easier to spot.

[crothmeier]

my 97 Chev 1500 is losing coolant slowly also. about a half jug every 3,000 miles or so. I re-did the water pump last winter, the oil is always fine when i change it, i dont know where its going, i dont care at this point (231,000 miles), i just check it when i change the oil and add. at least its not burning oil!!!

[IFallsRon]

Check around the outlet where your thermostat is located.

[pinkfloyd4ever]

Thanks for the tips, I was thinking about the thermostat after I posted actually that was one area I did not thoroughly check.

[ratmn218]

intake gasket,

[theoilman]

Many 4.3 V-6s, 5.0 and 5.7 V-8s share the same problem with the intake gasket (though the later ones were no where near as bad as 5 years earlier). GM aluminum intake manifolds on cast iron heads have very different rates of expansion and have a lot of 'creep' over the gasket. The gasket will crack because of the head/intake manifold sliding across it. Many times the leak starts very slowly and is internal - leaking coolant slowly into the valley - directly to the crankcase. Even slowly enough that engine heat will evaporate the water faster than make the traditional brown mess of water in the oil. A tell-tale of this - check the dipstick: if the upper end of it has water droplets or is rusty you may have this problem. As it gets worse the gasket then cracks at the ends causing a trail at the front or rear of the head.

When repairing ONLY use the best / most expensive intake gasket you can find - more layers, better bonded silicone rubber traces, etc. These will tolerate the creep better and last longer.

Originally GM used paper type gaskets here, the later years they changed to the better multi-layer gaskets.

The slow internal leak causes additional problems. The ethylene-glycol left behind in the oil causes acid buildup and premature crank, rod and bearing wear. I recommend also doing an engine flush to finish the job.

[Whoaru99]

Yup, I agree completely with intake gaskets.

Replaced intake gaskets on my 1994 with some McCord gaskets from one outfit and when it leaked again a year or two later, and the gaskets were super crusty upon disassembly, I decided enough of that. Second time I used some somewhat more expensive Fel Pro gaskets with the seal stuff like theoilman described and haven't touched it since. Probably been at least 5-6 years now, I'd guess, and no signs of any coolant loss.

And yes, it was all done per the factory service manual, including torque wrenches, etc.

[pinkfloyd4ever]

Ya, that was my fear that it probably is getting sucked in and burnt up. I did notice an area near the thermostat that looks suspicious so that will be the first undertaking here.

[pinkfloyd4ever]

rough guesstimate on cost to replace intake gaskets on the 92 1500 V6 anyone?

[berfish]

Check your gaskets. Water pump gasket? Intake gasket? I had the same problem and it has been fixed with a new water pump gasket. It only leaked when the engine was hot. And it dripped into my skid plate so I never saw any coolant on the ground. I think it is pretty common on older trucks that don't get used a lot and sit for a period of time.

[pinkfloyd4ever]

its getting pressure tested today, anything from lower hose to the gaskets. Quote on gasket was 600. The temp gauge just flies all over the board no reason to it, on a cold engine start it flips over to above 260 then will just swing back and forth. Gotta love the classic vehicles

[pinkfloyd4ever]

just an update here- ended up being radiator and lower hose gasket was ok

[theoilman]

Congratulations, you got lucky. Most of these are a whole lot worse.

[Dave S]

glad to hear it was something less serious. My sons '96 S-10 Blazer had a bad intake gasket as everyone mentioned and cost us $600.

It's not a question of if it happens, but WHEN it happens I would recommend what theoilman said about flushing out the entire engine.

[pinkfloyd4ever]

ya, this is just one of those vehicles that I plan to own until it rusts apart or blows up, and it was all flushed out

Related to this though- I haven't had any reason to discredit the mechanics so I believe them but riddle me this. Did this before during and after the radiator change and flush. The temp gauge just jumps all around with no rhyme or reason to it. I can start it up in the morning and the gauge will go all the way 260+ then will just swing back and forth, may settle down to below 110 jump back a few minutes later, on and on you get the pic. The mechanic said just probably just a messed up gauge because the cooling system is fine, unless I want to pay more $ to have them really look into it, which I said no. There is no change in the sound or tone of the engine at all.

Any ideas?

[Scott K]

I agree, sounds like a temp gauge.

[Whoaru99]

Temp gauge, temp sender, or maybe just a bad spot in the wire grounding out and giving a false reading.

[pinkfloyd4ever]

alright, thanks guys. I was paying attention to it some this morning and if I hit a bump or anything in the road that gets it going some too, so just going to ride it out! Thanks