Help with coolant leak under thermostat please

2001 V6 155k leaking a lot of coolant. Seems to be coming from around the bolt directly under the thermostat housing. The bolt goes to the bracket that runs under the alternator. Is the leak coming from the thermostat or am I missing something.

 

There are leaks that would be hard to tell if they're coming from the thermostat or the water pump since the water pump is covered by a metal cover. More pics and / or a video might help to tell exactly where it's coming from. There's a good chance you're going to have to get in there to see what's going on.

 

That's what I was thinking. It started the day it got down well below freezing, today was the first chance I had to wash it out and take a look. Thanks for the help.

 

The color doesn't look like coolant but I suppose it could be very diluted 'green' coolant.

In the area it is coming from, the likely culprit is the water pump is leaking. How many miles has it been since you changed the timing belt?

 

Yeah, it's diluted coolant. Not sure on the water pump. Bought the truck with 106k from a dealer. No notation on if the water pump and timing belt had been changed . Dealer hasn't done either one. Took it to my families mechanic after I bought it and he said it looked as if the timing belt was done. Of course there was no way to know if the water pump was done.

 

I would say most likely a gasket is leaking at the mating surface. the gaskets have holes for the bolts. Hard to tell from that pic. I always rub a thin coat of black RTV on both sides of coolant gaskets before install even if the gasket is new. peace of mind.

 

If you are mechanically inclined enough to replace the timing belt, it will cost you around $260 to completely replace all three outer belts, the timing belt, the tensioner pulley, the idler pulley (that the timing belt goes around), the two cam shaft bearings, the crank shaft bearing, the water pump, and the thermostat. The price comes from the e-Bay reseller and is for all genuine Toyota parts.

You'll hafta buy the crank shaft bolt direct from Toyota for (IIRC) about $8.

There is an excellent video that shows, step-by-step, how to replace those parts from "Timmy" on YouTube.

 

https://m.ebay.com/itm/15-Piece-3-4...MP-Genuine-OE-Manufacture-Parts-/180729034728

 

Did you ever figure out this issue? I just did my timing belt, water pump, thermostat and drive belts and happened to get this leak soon after.

 

Where is the top of the leak coming from - behind the H2O pump?

 

Same exact spot as in the picture.

 

That sucks - unfortunately I don't know if there's any way to figure out what happened besides opening it up again.

 

If it's leaking around the thermostat, why not just replace the thermostat and gasket? It would take you maybe an hour to do, the most time consuming part being drain and refill.

 

I'd at least look at that too. The worry is that it's running down from the wp and isn't visible until it hits the thermostat area. Still easy fixes hopefully work first.

 

Are the shafts around thermostat screwed in before tightening nuts?

 

The studs? Yes they can be snugged up gently before the nuts are torqued down.

 

I found a leak on my 02 that the alternator bracket bolt screws into a coolant passage, leaked around the bolt.
Took it out and used thread tape and sealer on the threads and no more leak.

 

I usually use aviation permatex on the threads that see water jacket areas, doesn't harden and seals real well.

 

Did you ever find the exact source of the leak or try something out that happened to work? Getting the same problem with no good viewing points.