Yenkohead

Hi there. I haven't been here in awhile but always appreciate the help and expertise on this board (I did do a search and some reading up on this before posting). My daughter has the 94 Z28. It has been starting to overheat to the point where I won't let her drive it until I figure out how to fix it. Here are the symptoms followed by what I have done:

Symptoms: Heats up to 260 way too fast, there is no heat inside the car, radiator fluid level somewhat low but not empty, noted that radiator hoses don't get hot, no leaks detected, no noise from water pump, fans kick on when really hot.

What I have done: Topped off radiator (I thought) with Prestone and distilled water, replaced thermostat, bled off air numerous times (most times only noted steam coming out), just now developed 2 leaks at side of radiator (stupid plastic tanks) - likely related to extended time of bleeding air and temp at 260.

At this point I am thinking about replacing the radiator, which will necessitate flushing the system (and may clear out any clogs in the system). Is there a way to rule out a problem with the water pump? Or should I go ahead and replace it while the radiator is out? I am crossing my fingers at this point hoping I didn't damage the block in any way (although I wouldn't mind rebuilding it since it just turned over 200,000 miles).

Any thoughts on possible fixes or suggestions on next step?

Thanks,
Greg

slick1hunting

The plastic tanks can be replaced on many radiators( may save you a few bucks). Be certain all hoses are routed correct. From what I see the overflow gets switched(it should be the top of filler neck). Was the thermostat lt1 as they are different than sbc. If your not familiar with shoebox's website I would find it and bookmark it as its an incredibly valuable tool for lt1 owners.(loaded with pictures and instructions and so much more). My bird had so much little pebbles in ac condensor and radiator it acted as a heat sink. If it were me I would pull radiator and have tanks replaced or get a new one and then confirm all hoses are routed correctly and fill and bleed per recomendation on shoebox. Good luck.

Yenkohead

Thanks for the reply. Did not know about replacing the plastic tanks. Hose position should not have changed (no recent engine work). I will check on the thermostat type - I got it from a local Autozone - many of those guys just work the cash register so............... I also forgot to mention that I put the old t-stat in some boiling water and it did open up. And did check out Shoebox's site and even saved a few pics from it to locate the bleeder valves and the lines going to the heater core. I figure this will be a good time to do a good flushing of the system while I have the radiator out of the way. With the high miles I may as well replace the water pump too.............heck, I should just yank the engine and rebuild it - I could see a nice 383 going back in there.

Thanks again. I'll try to give an update when I know more.

Greg

kevhogaz

With the quick rise in temp, and no heat from the heater, it sounds like you're low on coolant. I'd try bleeding the system again, and go from there. You'll be able to see coolant flowing thru the radiator, if the water pump is functioning correctly.

Yenkohead

You know, that makes a lot of sense. I noted that I seemed to keep adding and adding fluid, and when I was opening the bleeder valves there was a lot of steam and rarely any fluid coming out. Eventually I seemed to get pressure building up in the radiator and that is when I noted a pair of leaks near the top of the tank below the radiator cap area. So maybe this has been going on for awhile (and I wasn't told until now about it)............kids!

Thanks man!

Greg

Fatdog2

sounds like a clogged radiator.I would take the car to a mechanic to check out the system.If you continue overheating,you could damage the engine.My02.
P.S. We are all here to save money fixin things ourselves,but you have a serious problem here.Hope this helps.My02.

Yenkohead

Well, here's an update. I am in the middle of backflushing the cooling system and noted that there is water dripping from the front of the engine block (it's hard to see exactly where with all the "garbage" in the way). It seems to be in the area of the water pump but could spell a cracked block I suspect. Just what I needed.

OK, new update: I just found that the temporary hose that I was using for the back flush is leaking above the water pump - tightened it and no more leak. Whew!

I went ahead and ordered a new radiator (rather than just the plastic side tanks as they require a special crimping tool) and plan to pick it up in the morning.

New problem: In making room for the new radiator and disconnecting everything I found the lower "brake line" fitting is rounded. Does anyone have a trick to get this connection loose so that I don't have to replace the whole hard line? I hate when those things get rounded off!

Thanks!
Greg