Coolant leak...

smac

Registered User
So it's dripping from under where the metal part of the upper radiator hose connects to what I assume is either the pump or the block. Couldn't see much last night cuz it was dark. But it drips pretty steady while it's running and stops after a while once it's off. Ideas...?
 
At the engine, the upper hose connects to the thermostat housing, which is notorious for leaking where it mates to the intake manifold, usually after an R & R.

The pump itself should have a weep hole under the snout that typically indicates wear in the bearings/seal, meaning time to replace.

I'd clean things off, and take a good look with plenty of light in any case. Might need to be pressurized with a tester if you can't find it.
 
How much does it cost (parts), and how hard is it to fix, assuming I have decent mechanic skills?
 
You could replace the thermostat gasket with a new one, at the point where the black metal thermostat housing mates to the upper intake manifold.
 
How much does it cost (parts), and how hard is it to fix, assuming I have decent mechanic skills?

Example just for the thermostat housing re-gasket (Autozone prices):
  • Gasket: $1.50
  • Sealer: $4
  • Antifreeze: $12
Additional if you want since you're in there:
  • Thermostat: $5 ~ $14
  • Upper hose: $10
  • New clamps: $5 ea?
Outright it's not a complicated job. Just keep in mind that sometimes it is difficult to get the thermostat housing to seal properly, so any repair needs to be done carefully to avoid the need to do it over - be sure both surfaces are clean and flat.

Also getting the thermostat to lock in place and stay positioned during installation can be tricky - pay attention that it is not in backwards.

Getting the bolts out if they are stuck can be a chore, especially if one breaks during removal. Be sure to clean the connector and post on the temp sender.

If the housing is badly rusted, warped or bent, it might need to be replaced. Sometimes you can source a good one here from another owner. Pricing depends on them. I think last one I sold was $35 plus shipping.

In your case, it might just be a loose clamp at the upper hose to the thermostat housing, so don't make any plans/decisions until you know exactly where the leak originates.

Please keep in mind that small leaks on our cars are usually a symptom of the cooling system needing attention overall. If the thermostat housing is rusted, as an example, it might mean that other components are equally 'aged' and in need of replacement.

By the time you replace the radiator, cap, thermostat, water pump, hoses, belts, gaskets, heater core, coolant etc. things add up - our cars depend heavily on a correctly performing cooling system, and like any older vehicle, things don't last forever, so plan repairs accordingly and good luck.

Ken
 
Last edited:
So I got a gasket and Permatex water pump and thermostat housing RVT silicone gasket maker (which I was told works as a sealer). Do I apply this stuff to both sides of the gasket or just the nonadhesive side?
 
Do I apply this stuff to both sides of the gasket or just the nonadhesive side?

I install the thermostat into the housing (cleaned, surfaced and painted), then apply adhesive to the housing, then let it set a few minutes, then place the gasket onto the housing and let that sit 10 minutes, then apply a thin coat to the gasket and a good coat onto the manifold where the housing mates up. I let that sit another 10 minutes, then assemble, with a small amount of adhesive onto the first few bolt threads. I let the whole thing sit overnight before attaching the hose and adding coolant.

Be sure to air bleed the system carefully when adding coolant using the stand off bleed bolt on the thermostat housing. Get it loose before the housing is off the car and confirm the bleed hole in the bolt is clear. Notice there is a place on the stem for a wrench so you don't twist it while removing the bolt.

I don't recall the gasket having it's own adhesive on either side. What brand gasket is it? Does it have 4 holes (1 large & three smaller)?

Don't bother putting it all together until you make sure the housing is clean and _very_ flat, with no rust, gouges, etc.

Did you already confirm that is where the leak is from?
 
Last edited:
Oddly enough, the leak is from the bypass hose next to the thermo housing. Something which my wife, who knows nothing about cars, pointed out. I had just fixed it last week and she said 'What if you didn't tighten the claps enough?'. Go figure.
 
Back
Top