GKK

On my "91" L98, I've been noticing a tiny puddle of coolant near the middle of the engine on the drivers side near the #5 and #7 cylinders. It only appears intermittently (it's a daily driver).

I don't have an oil cooler so, it can't be the oil cooler lines. The coolant leak just re-appeared after being gone for the last 6 months. I know the L98 has a head gasket problem but, I thought a blown head gasket would leak coolant internally.

The engine runs fine and just passed a smog test with flying colors. The engine runs at normal operating temps and never even gets close to overheating. Also, I've never had to add coolant to the radiator.

Any help is really appreciated.

SunCr

Sounds like the intake gasket may be leaking, though the coolant passageway is a long way from 5. 6 mounting bolts. From the front, passageway is between the #1 & #3 bolt; rear #5 and #7. Make sure the upper hose is tight at the thermostat. Oil cooler lines run to the oil filter. If you replace the gaskets, you need GM#12525814. Those gaskets have the Retainers and Coolant Restrictors - unique to the '91 Vette. Dealer only.

bogus

yea, check the intake, it would be my first point of reference. Also, clean the area around the plugs with some brake cleaner and remove said plugs. This will tell you if there is a weaping head gasket. When I did this to bastet44's 87 coupe a couple years back, #8 was filled with coolant, not good.

Also, I agree totally, check the lines to the oil heater. It has 4 separate connections down there, between the metal lines to the rubber lines, the heater and the block, plus, the metal line can corrode.

I would check it, then simple green the area and hose it, fire up the car and watch it... if it's leaking there, you will see it under pressure.

is the engine running hot at all? If not, I would think the problem is rather minor.

GKK

I replaced the intake gasket with the Felpro TPI set and the "Right Stuff" about a year ago and all was fine. I didn't see any oil cooler lines going to the oil filter like my "89" Vette had.

The engine never over heats and all is normal except for a six inch long little stream under the engine every once in a Great while. When I drive home from work and I look under the Vette in the morning, everything is dry. Some days, when I go to the gym in the morning and return, about an hour later I see the coolant.

The waterpump, radiator, thermostat, radiator cap, coolant and coolant hoses are new and dry. This just bugs me.

bogus

wow. that is annoying.

on the drivers side of the block, there is a fitting where a 2nd knock sensor would go. I wonder if that is weaping. It's also where the oil heater would attach.

GKK

I just took a closer look near the #7 spark plug and knock sensor area and even felt around with my finger but, all I felt was old dried up oil.

I looked underneath the engine again and saw a new coolant puddle so, I grabbed my flashlight and carefully traced the area and found some damp oil sludge near the top of the waterpump but, everything around this area is dry to the bone waterpump, hoses, back of pulleys, waterpump weep hole, front of the block etc...

I suspect that there must be a minor leak maybe from the coolant temperature sensor or throttle body coolant bypass hose enough for it to drip occasionally and then dry up from the engine heat making it hard to trace.

I just washed down the front of the engine with simple green and I'm going to check it out immediately the next time it leaks. The head gasket is not the problem as I thought earlier, fortunately!

Thanks so, much for the help SunCr and bogus! I really appreciate it!