Nathan Plemons

A friend of mine was having trouble with his 95 Z-28. This thing has had a rough life, but overall is in pretty good shape. It's bone stock, all the way down to the paper air filter.

Since he's purchased the car his low coolant light has stayed on and his low oil light has also stayed on, even though both have been full. Well anyway we ordered both new sending units from Jeff Kopp :) and he came over last night to install them. We did the oil first, no big deal. Then we did the coolant level thing. We were expecting to dump some coolant but to our suprise when we pulled the sending unit out, nothing poured out. Airlocked maybe? So we removed the radiator cap and wouldn't you know it that we couldn't see anything in it!

The overflow reservoir was bone dry too. We put the sending unit in and topped off the radiator. It didn't really take much water, about a 1 liter (no I haven't gone metric we just had a 2 liter bottle to fill it with) I filled up the reservoir too (WAY UP) and we fired it up. It started circulating just fine and the low coolant light didn't come on.

I guess now when the light comes on he can believe it, but where did the water go? I filled it up myself! It doesn't appear to leak out from anywhere, there is no evidence of oil in the water and there was no evidence of water in the oil. The car doesn't emit any white smoke so I don't think it's burning it either? I wouldn't really be suprised if the car has a blown head gasket, but it doesn't seem to have any of the symptoms.

I doubt the car is just thirsty.

Ron78Z&66Vette

When you initially filled it did you do it with the bleed ports open? If not, you won't get a good service and your cylinder heads will have "hot spots" from air pockets

Nathan Plemons

Yup. We made plenty sure that we got all the air out of there.

I honestly think that his surge tank has a slow leak in it. Something slow enough that you can't see it but after the tank empties and then it expands into the tank, the tank empties again, and the radiator goes sucking air.

Problem is that you can't even see the freaking tank.

SPD DMN

Check all the hoses when the coolant is hot and there is a good deal of pressure in the system. It may be such a slow leak that is will not puddle but may burn off before it hits the ground.

Red Dwarf

Get a pressure check.............................

Nathan Plemons

Not a bad idea at all. Actually I just thought about it, I have a UV test kit that came with several dyes for different fluids. I used the dye for motor oil, but not the coolant. I may see if he wants to dump that in there, run it for a few days and then bring it back by.

ZBRA

The overflow tank/battery tray is pretty cheap new if I remember right.

oldace84

Blown head gasket.....cracked block.....any condensation in the oil filler cap?????

just a thought...sorry...

tony :smash:

Nathan Plemons

There didn't appear to be. You know usually if you get coolant in your oil it'll form that nice frothly brown sludge, no signs of that. There also weren't any signs of oil in his radiator.

What does worry me though is that we've drained and "flushed" his radiator several times and the coolant is still very murky looking. I assume we've just never got the block flushed real good. Some day we'll just pull the knock sensor out of it and drain it completely. I just wish he had an electric water pump, that makes the flushing job so much easier.

sunrise.cm

Possibly a blown head gasket. Get a pressure tester and pressurise to 15 Lbs. on cold engine and look for leaks. If you don't see any, remove spark plugs and look for evidence of coolant. If you have a good tight system, it should hold pressure for quite a while -- at least 5 min. After changing head gasket, and H2O pump, I checked mine for 30 min and it held with no noticable pressure loss. Hope it helps. :smash:

VBP

I've seen the heater core leak slow enough where it didn't pour on the passenger floor but slowly leaked out the drain for the A/C condenser. Just a thought. :flag

MrJay

Is it a auto car? if so then check and see if he has any in the tranny because the trany cooler can be leaking that is what happpend to my S10.

Jay

Nathan Plemons

good idea, but it's a 6-spd.

I'm thinking it might be leaking at the heater core like VBP said. I was talking to my friend today and I asked him if he had checked the coolant level again. He said he hadn't, but yesterday night he heard a sizzling sound when he parked the car. He found a liquid dripping on his exhaust but it was pretty dark and he couldn't tell where it was coming from. I immediately thought this was just condensation from the A/C system, but who knows. I'll certainly take a closer look.