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Discussion Starter #1
Most likely from the thermostat housing area making it's way onto the exhaust. Exact source location(s) to be determined, but I have had some leaking from that area for quite some time, just not this bad! As in there is a steady drip right now. I've been avoiding fixing it due to the chronic broken bolt issue that often comes up there.



Hard part will be determining if this is the leak or if there are other leaks in that area.

Anyone noticing anything obvious, besides the leak at the thermostat housing?



There is coolant under the heater hose here. I have no idea if it's the hose itself or dripping into the hose:


If I end up replacing this heater hose (DAYCO 88394 ???, GATES 19661???), what size OE style hose clamps do I use?

The upper radiator hose seems fine, except for a mechanic used a worm clamp which I intend to replace with an OE style spring clamp which I already have.

Unless I am missing something, is there anyplace else where coolant can drip down onto the exhaust? It is unclear to me how a leak in the front of the thermostat housing can get onto that hose in the back as well.

If I can't find another obvious leak, seems to me that the thing to do is to fix this one with Fel-Pro 35477, with RTV on both sides, and reassemble everything except with OS style clamps on the thermostat housing hoses. Would need to get the thermostat housing clamp for the smaller hose though.
 

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Discussion Starter #3
Or the hose is bad on the bottom part. Will be easier to inspect once I have the thermostat housing is off. Will try to presssupre the system first.
 

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Discussion Starter #5
Got it on the coolant system pressure test kit loaner tool from Advance Auto Parts. It's definitely leaking from where the thermostat housing bolts onto the engine. I'll report back how many bolts I break off when I remove it.
 

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Discussion Starter #6
The top bolt holding on the thermostat housing broke! The other two I got off fine. Will post a picture once I get the housing off (It doesn't want to come off).
 

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Discussion Starter #7 (Edited)
The housing eventually came off. The remnants of the broken bolt were holding it in. This is what it looks like now:


I have sprayed it with some PB Blaster. I am looking for some recommendations for removal. I may wait until tomorrow to even attempt removal. My first guess is to try a small pipe wrench???
 

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Discussion Starter #9
Now that I have cleaned up everything, it's clear that the leak is from the bypass hole portion of the thermostat housing. That's a definite weak point worthy of extra RTV.
 

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Discussion Starter #11
I got the broken bolt out!!! It literally just unscrewed by hand!



I think rust around the hole where the bolt went through the thermostat housing rusted it together there. I had to hone out those thermostat housing bolt holes with a drill bit on a drill press. Even better, I have a spare bolt the same size (picked one up at a junkyard once, since I've been expecting this to happen for some time.
 

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Discussion Starter #14 (Edited)
OD of heater outlet is .75", .8" if you consider the lip.
OD of radiator hose pipe is 35mm (1.375" or 1-3/8"), 37mm (1.45" with lip).
I wondering if a 15/16" or 1" spring type hose clamp, possibly obtainable at a local hardware store would work on the heater hose side. I see them on Hillman's website here:
https://hillmangroup.com/us/en/Fastening-Solutions/Specialty/Automotive/Hose-Clamps---Auto/c/541HC .

The three thermostat housing bolts are M6-1.0 threaded bolts with 8mm heads. Normally M6 bolts have a 10mm head. I have no idea if using bolts with a 10mm would matter here. The length is 27mm, but only 25mm is threaded.
 

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I don't recall if the holes go right through, you could poke a wire in them to check.
Hardware store bolts are inferior to original ones because the latter generally have a washer type head. You can put a washer on a regular hex head bolt, but it usually will be sloppy, oversize and look like a substandard repair.
 

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Discussion Starter #17
I don't recall if the holes go right through, you could poke a wire in them to check.
Just did. Bolts are not exposed to coolant!

Hardware store bolts are inferior to original ones because the latter generally have a washer type head. You can put a washer on a regular hex head bolt, but it usually will be sloppy, oversize and look like a substandard repair.
I have been mail ordering stainless steel flanged bolts with the washer type head.
 

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Discussion Starter #18
Got it back together. Had to leave off that bottom bolt on the coil bracket. No way to get a ratchet or wrench on that, and probably won't miss it. Will refill coolant sometime during the week and report back. Not completely sure if this was the only leak since when pressure testing got a lot less leakage than when warmed up running, which to me indicated that the leak was worse when the engine is warm.
 

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I always have trouble getting that bottom bolt back onto the coil bracket. I use an 8mm (or 5/15") socket that is a 1/4" drive, with extension and ratchet. I have to sort of push down on the rubber tube going past that point. My little sockets are fairly thin.
 
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