Antifreeze leak

[ralph92ZR1]

:dancing I would appreciate some advice. My Z is leaking antifreeze only when it runs, within 5 minutes, dripping below the lower cross-frame member. I have the front end up on jack stands, ran it, and cannot spot the leak. The telltale drip is on the underside cross member and I have used a mirror, light, etc to spot the source of the leak. I have checked all hose fittings, and to get to the hose entering the block, have removed the belt tensioner and serpentine belt. I cannot feel any leak around the water pump gasket or the water pump pulley, but have not removed the pulley itself. The small puddle inside the cross member is below the hose clamp on the hose entering the block but could also be below the water pump pulley-hard to tell. The pulley has no play in it and the mileage is only 19,000. So here are my questions:

Is it ok to run the engine briefly (5 minutes) without the belt to better view those areas??? WILL NOT ALLOW TO GO ABOVE 130 F.
Anything I have not thought of ???


Thanks for the advice :handshak:

[QB93Z]

I had a coolant leak on my 1990 ZR-1 right after I bought it last year. I could not find it with a visual inspection. In ended up getting a coolant system pressure tester. The leak turned out to be from the radiator. The right end tank had small cracks. I replaced the radiator, all is OK now.

My symptoms were the same as you are describing. The coolant would puddle under the front cross member. A lot of the coolant system is "above" that cross member. The problem with finding slow leaks is that you have to be a operating pressure to track them down.

I would caution against prolonged running of the engine with the belt off. There really is no way to tell what engine temperature is without the coolant circulating.

I live about 2 hours from you in Westminster, MD. If you would like to meet up some where I would be happy to help you find the leak. I am available Sunday afternoon. Have Tester, Will Travel.

Jim
443-244-1347

[secondchance]

"I could not find it with a visual inspection. In ended up getting a coolant system pressure tester. The leak turned out to be from the radiator. The right end tank had small cracks. I replaced the radiator, all is OK now."

Same here.
You might be able to see through opening on the shroud with a flashlight depending on where it is cracked.

[ralph92ZR1]

Thanks for the info and the offer but hesitate driving to Maryland with the leak. Will look into a pressure tester. Appreciate the response.

=D>

[ZR1Vette]

If your reference to 'cross member' is this item>>>
http://i17.photobucket.com/albums/b79/MRBLU/ZR1crossmember.jpg

then another item to look at is the mesh covered hose.

I would check the clamps (eg tighten) for the hose that goes from the water pump to thermostat housing... hose looks like this>>
http://i17.photobucket.com/albums/b79/MRBLU/ZR1coolanthosefromwaterpump.jpg

Also would carefully inspect the hose itself (since it is mesh covered might be hiding a small defect).

[XfireZ51]

You can usually get a pressure tester on loan from Autozone or Advance Auto.

[LGAFF]

The downpipe hose that runs down behind the fan is a common place where the hose can rub through......happened to the 24hr endurance car, and my 92.

[GOLDCYLON]

Are the waterpump bolts tight? The pooling leads me to beleive this is the issue

[Jeffvette]

Pressure tester is the only way to verify where the coolant is coming from.

Disconnecting the fan belt is not going to help you solve where the leak is from, as it won't be building any pressure inside the system.

[Locobob]

Pressure tester is the only way to verify where the coolant is coming from.

Disconnecting the fan belt is not going to help you solve where the leak is from, as it won't be building any pressure inside the system.

Jeff speaks the truth :thumbsup: Finding a leak with the engine running is no easy task.

[White Bullet]

If your reference to 'cross member' is this item>>>
http://i17.photobucket.com/albums/b79/MRBLU/ZR1crossmember.jpg

then another item to look at is the mesh covered hose.

I would check the clamps (eg tighten) for the hose that goes from the water pump to thermostat housing... hose looks like this>>
http://i17.photobucket.com/albums/b79/MRBLU/ZR1coolanthosefromwaterpump.jpg

Also would carefully inspect the hose itself (since it is mesh covered might be hiding a small defect).

I vote for the radiator but pressure testing is the way to go.

ZR1Vette, Nice detailed car :thumbsup:!

[GOLDCYLON]

Any updates?

[ZR1@LAST]

I vote for the radiator but pressure testing is the way to go.

ZR1Vette, Nice detailed car :thumbsup:!

Thanks for the visual. Agree, nice detailed car and shop/garage :thumbsup:

Jeff
90 ZR1

[Gary Yarbrough]

I am among those that had a similar problem and it turned out to be cracks in the right end tank. I also replaced the radiator and everything was back to normal. I found the cracks by using a small mirror and a flashlight.

[ralph92ZR1]

I first took the easy route; removed the belt tensioner and belt. Could access the hose clamp into the block. Snugged it up and also the rest of the hoses and clamps. I have Samco hoses that are only 2 years old. Have the front end up on jack stands and level. Have ruled out the radiator since no air flows, etc. The crossmember I am talking about is the one that can be removed to access the front oil pan bolts. Anyway, still leaks, and comes out dead center on the center of the cross member. Now the question is it the water pump bearing, the gasket, or bolts. The bearing assembly seems tight (no play). I can reach in and feel a wet area on the lowest portion of the water pump. So I guess to really tighten the bolts, I will have to drain the system and remove all the hoses and pump pulley?? Once I do that, I would hate to put everything back together and wish I had replaced the gasket and pump anyway. You mentioned the bolts. Is there another way to access and tighten???
I appreciate your thoughts and any suggestions because this will take some time for me to do, but I do enjoy working on the car.
Thanks again.

[secondchance]

I first took the easy route; removed the belt tensioner and belt. Could access the hose clamp into the block. Snugged it up and also the rest of the hoses and clamps. I have Samco hoses that are only 2 years old. Have the front end up on jack stands and level. Have ruled out the radiator since no air flows, etc. The crossmember I am talking about is the one that can be removed to access the front oil pan bolts. Anyway, still leaks, and comes out dead center on the center of the cross member. Now the question is it the water pump bearing, the gasket, or bolts. The bearing assembly seems tight (no play). I can reach in and feel a wet area on the lowest portion of the water pump. So I guess to really tighten the bolts, I will have to drain the system and remove all the hoses and pump pulley?? Once I do that, I would hate to put everything back together and wish I had replaced the gasket and pump anyway. You mentioned the bolts. Is there another way to access and tighten???
I appreciate your thoughts and any suggestions because this will take some time for me to do, but I do enjoy working on the car.
Thanks again.

If I understand your post correct, leakage is between the water pump and the block?
If so, although it has been a few years, after water pump replacement I noticed water was still seeping through a week later. I was able to access all bolts (can't remember if I removed the pulley) with extension and a socket, tightened up a little more and all was good.

[GOLDCYLON]

If I understand your post correct, leakage is between the water pump and the block?
If so, although it has been a few years, after water pump replacement I noticed water was still seeping through a week later. I was able to access all bolts (can't remember if I removed the pulley) with extension and a socket, tightened up a little more and all was good.


Correct, this was my guess in post #8 as well due to the pooling on the crossmember. I beleive the waterpump is the culprit which could be as simple as tighting the bolts, replacing the gasket or the waterpump itself is shot and bleeding out. If you end up replacing the water pump put the bolts as you remove them into the same postion in the new waterpump one at a time on the floor of your garage or work bench. The bolts (several) are differnet sizes, head types and lengths. When you pull the pump replace all the bolts back into the old pump from the new pump and reinstall using the old pump as your guide.

[secondchance]

I hope it just needs tightening.:hello:

[Jeffvette]

Go to your local parts house and borrow/rent a pressure checker.

[billybaloneey]

I agree with the suggestion to use a pressure tester. You won't have to worry about moving belts and hot hoses while looking for the leak...most leaks should be easy to see and hear.

You can borrow or rent one. They are not that expensive to buy and if you do you'll have another cool tool in your collection. Some of the better testers come with various adapters that will allow you to test the cooling system of more than just your ZR-1. The well known Internet auction site has lots of them available.