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Coolant leak / 89 GT

J89Sally

New Member
So as the title reads I have a coolant leak and trying to see where else to check.

Here is the list of brand new parts.
Water pump and gasket in front and behind plate
Thermostat housing, thermostat, and gasmet
Timing cover
Front main seal
Timing cover gasket
4 hoses (upper, lower, and both that connect to water pump)
New clamps on hoses

All is good and snug, no loose bolts. Coolant is just over mid-way to top in radiator. Yet... coolant is leaking. There was a small "pool" in the dip of top right corner of Timing cover by that bolt that holds Timing cover to motor. More on drivers side and just a lil bit by passenger side just under thermostat.

Both bolts which are hard to reach are very tight and snug.

Please help with where to look for the leak or what else to check.

I couldn't do a pressure test cause from right under the cap to the pipe in the radiator that holds the fluid there is a gap. A good 4" gap or so. So once I hooked up the powerbuilt brand cooling pressurized pump, it wasn't doing anything as air was pushed in but with that gap it wouldn't pressurize.

I'm off work all day tomorrow and trying to avoid a shop but if need be a shop is my last resort.
 

broncojunkie

Well-Known Member
Did this leak start right after replacing all those parts, or did you replace them in an attempt to fix the leak you're referring to?

Without seeing it in person, my first thought would be the t-stat housing. I see you have replaced it, which is why I was asking if the leak was there prior to your repair. I've heard lots of folks having issues with aftermarket housings not sealing.
 

J89Sally

New Member
First issue was water pump. Old one locked up. Replaced water pump and gasket. Got that sealed nice and tight and while I was at it. I did thermostat/housing and gasket. Small drop from front main seal....

Now no drip from bottom but just in that area as described. If it's the housing I'll double check.

Any other suggestions? I'm really to figure this out. Also the new housing is 100% the same as old its just a polished look as opposed to a grey color. If that matters
 

broncojunkie

Well-Known Member
What I've been hearing is that the machining on the new housings aren't very good. I've also seen the thermostat slips out of position and causes it not to seal properly.

There are a couple other things in the area that could cause it, such as the intake gasket (although they typically leak coolant into the crankcase), heater bypass hose, and the upper radiator hose. None of them are as prone to leaking as that pesky t-stat housing!
 

J89Sally

New Member
Damn sounds like the tstat housing...could be it I still have the original (I believe.. im not home at the moment) and all hoses and clamps are brand new. Clamped down snug snug too.

It would make sense if it's the housing cause the leak is coming from up top. Now if the intake manifold is leaking down to the crank case it would cause coolant to come out of where?

Also what would explain the thermostat not kicking on to keep temp low? My temp gauge went up to 260 of 270..?
 

broncojunkie

Well-Known Member
If coolant is leaking internally, it would show up on your oil dipstick (and won't be pretty lol... ask me how I know!)

As for your temp spike, it's hard to say. I wouldn't think a poorly machined thermostat housing would cause it not to open, but I suppose if the thermostat slipped out of position before you tightened it down it could cause it. Also, make sure it's not in there upside down. That's a common mistake. I know how they go in and I've still done it myself. You also could have simply got a bad one. These chinese parts are hit and miss (and yes, most of the parts we get are imported).
 

Blueknights75

Active Member
Great point @broncojunkie! These parts are definitely not made the same. I had two Motorcraft TFI modules bad out of the box from LMR and finally the third one worked like a champ. Had a bad egr sensor bad out of the box from LMR as well.
 

broncojunkie

Well-Known Member
Don't get me started on TFI modules lol! I needed one pretty bad a few yrs ago and picked one up at a parts store. Car still didn't run. I tested everything and it kept pointing me back to the tfi. After 2 or 3 trips back to the parts store with the guys behind the counter assuring me it was something else, I went ahead and purchased another one. They wouldn't allow return of electrical parts, so I was stuck with the first one I bought. Before leaving with the 2nd new module, I had the guy bench test it on their machine. It tested bad. They had 3 in stock and all 3 tested bad. He apologized and gave me a refund on both modules lol! It's getting harder to find good aftermarket parts, that's for sure.
 
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