Coolant Leak Troubleshooting Steps

[TheBestCow]

Is that thermostat OEM and is that rust?

OEM out of a Toyota/Lexus red and white box from PartSouq.

Buddy of mine said it looked fine just that I had been sitting on a shelf for a while... wasn’t sure if that was supposed to be 100% black or if there is some kind of material on top... it doesn’t look or feel like rust.

 

[94SRUNNER]

I will go out an snap a picture of the new OEM thermostat I have on my shelf for comparison. (FWIW, I also got it PartSouq).

 

[TheBestCow]

I will go out an snap a picture of the new OEM thermostat I have on my shelf for comparison. (FWIW, I also got it PartSouq).

Appreciate that. Been looking for product photos online and something like this looks similar? Genuine Toyota Thermostat & Seal 76°C 90916-03089 - https://www.roughtrax4x4.com/genuine-toyota-thermostat-seal-76-c-90916-03089.html

 

[94SRUNNER]

Ok. So mine looks identical to yours. I think that rust looking material is an epoxy or sealant of some kind.

 

[TheBestCow]

Ok. So mine looks identical to yours. I think that rust looking material is an epoxy or sealant of some kind.
View attachment 2661553

Thanks for doing that. And the thing at about 12 o’clock on your photo is the jiggle valve that goes between 11 and 1 on install, right?

any other tips for thermostat or the hoses? Anything needed to help lube the hoses to get them onto the pipes? Trying to avoid rookie mistakes.

 

[94SRUNNER]

Yes that is the jiggle valve which ideally you want at 12 o’clock.

biggest tip is to take your time taking things apart and putting them back together again.
Additionally take care in coolant system burping process. Search it and you will find several step by step instructions. @2001LC typically puts it in coolant system related threads.

 

[2001LC]

Yea I went ahead and removed it last night and filled in just the holes and scraped, as best I could. Not perfect, but definitely not thick and lumpy. End result while it cures. Going to give it a full 24 hours and put the hoses on tomorrow.
View attachment 2661151

Great. The idea is to fill holes, so coolant will not get in them. Otherwise, the stagnate coolant will continue to eat hole metal.

Checking all the ordered parts before my 7 year old and I start tackling this tomorrow.

Newbie question here... is the new thermostat supposed to look like this with the discoloration on top?

View attachment 2661459


Any other pointers for removing all of the hoses, the oil cooler coolant hose, etc.? Any special lubing I’m supposed to do before connecting hoses? How high or low on a hose should the clamp be?

Rather ask a basic question and get it right than to not ask and get it wrong. I know I can try to mimic what is already there from a clamping standpoint, but just wanted to triple check.

That rust color is a special coating Toyota has on the thermostat, not rust. I see old used high mileage ones, where the coating is wearing off.

Always replace gasket (O-ring), anytime thermostat housing (inlet cap) removed. Same applies to any gasket or o-ring.

Place jiggle valve at top (12 o'clock).

Sung down the 3 nuts evenly, than torque to 14ft-lbf. Don't over torque to stop leak, it's not household plumbing!

Place OEM clamps back in same orientation as they came off. That is to say, into same impression, left in rubber old belts.

Position clamp on new belt, near center closer to outer edge.

 

[TheBestCow]

Had to remove the air intake to get a better grip on the thermostat housing to get the end off. Was going to clean the throttle body anyways, so this just forces the issue.

However, with that better view, I see this.

So does this mean the O-ring on the water inlet housing is likely leaking? Part # 9676135035?

Or perhaps that and/or the FIPG for the square and then leaking to that bolt hole? @2001LC

 

[2001LC]

Since I do not see pink in the round groove of water inlet housing. Not likely leaking at large O-ring. If you see in the groove (opening) than yes, likely large O-ring.

But from what I do see it could be small O-ring of water crossover pipe coming from heater Tee, into water pump.
Also could be top of water pump gasket.
Also water inlet rectangular fitting, which is only place Toyota calls for FIPG 1282B.

Coolant leak at water inlet and..

Working on a 00LC w/169K miles. Note: title is only starting point, much more was done. First up is getting coolant leak(s) under control. Coolant leak repair is the most important thing we must fix. Then I'll move on to Power steering leaks and other issues. The water inlet to water by-pass...

forum.ih8mud.com

 

[2001LC]

With the 98-05, we can remove throttle body and take off water bypass front. I do this often to replace it's gaskets or the water bypass itself and gaskets at points it mounts to head..

 

[TheBestCow]

Since I do not see pink in the round groove of water inlet housing. Not likely leaking at large O-ring. If you see in the groove (opening) than yes, likely large O-ring.

But from what I do see it could be small O-ring of water crossover pipe coming from heater Tee, into water pump.
Also could be top of water pump gasket.
Also water inlet rectangular fitting, which is only place Toyota calls for FIPG 1282B.

Coolant leak at water inlet and..

Working on a 00LC w/169K miles. Note: title is only starting point, much more was done. First up is getting coolant leak(s) under control. Coolant leak repair is the most important thing we must fix. Then I'll move on to Power steering leaks and other issues. The water inlet to water by-pass...

forum.ih8mud.com

View attachment 2662006

Does the o-ring go on the pipe directly below the throttle body?

Is there any way to determine what it is without taking the inlet housing off?

My guess is I'm going to have to remove it to see -- so would mean replacing the o-ring and fipg on the housing either way?

I have triple checked and see no leaks around the front water bypass bolts.

Dealer has the inlet housing o-ring in stock, would have to call back about the other o ring you mentioned. Is it 9676124019?

 

[TheBestCow]

Also, any pointers for getting the inlet housing off of the bypass? I’ve got the two 12mm bolts out but it is not budging.

 

[TheBestCow]

This is where I got to today:
- thermostat cover off, thermostat out
- removed all front heater hoses
- completed one side of all hoses, clamps, etc. for heater tee
- for other side have two hoses clamped at the non-heater tee side, still have to attach the heater core hose, clamps, and heater tee

What I'm stuck with:
- I cannot get the front water intake housing off and don't know how aggressive I can be with it - figured better to ask than to be aggressive and break something. I got the two bolts to break loose and have them removed.
- since I think this is clearly where the leak has been (along with both front inlets as seen in original photos) I am not going to tackle rear heater hoses, they look fine, and impossible to get to with the heat shield and might not tackle the oil cooler hoses, also look fine
- still need to clean throttle body and replace PCV valve and grommet

I am exhausted. I had to lay a piece of wood on the top of my step ladder and balance it on the engine to be able to tackle the heater tee area. With the lift on the Cruiser, just didn't seem possible any other way. Old hoses would not come off so had to cut them to split and peel off. Fairly confident they are original so when heater tees when done by previous owner they just swapped the tees and that's it.

Didn't mind the new black clamps - they came in the bag "locked wide" so it would slide into position really easily.

Biggest question is how to get a stuck water intake housing off. cc @2001LC since you seem to know everything!

Also, let me know if any of this looks wrong. Tried to make sure I got the clamp as close to the first "ridge" of each pipe as possible per the FSM.

 

[TheBestCow]

Waiting for my wife to become available so I can crawl on top of the wood on top of the engine. While I wait decided to clean the TB before breakfast. Going to look up the PCV valve replacement threads too. Before and after of cleaning throttle body. Not perfect but a lot better. Anyone think it’s been cleaned in 244k?

 

[TheBestCow]

Good news. I got the inlet housing off.

Bad news. Not sure if I bent the tube thwacking on the whole thing with a piece of wood and a mallet. It was not coming off. Understood I might break it.

Also, still not sure where it might’ve been leaking. It looks a little damp despite not having run for a few weeks because I sprayed some water in hopes of encouraging the o-ring and grime would loosen up. My hypothesis is the o-ring based on 2nd and 3rd photos — gunk at bottom of female receptor in 2nd photo, 3rd photo showing o-ring looks gunky and a spot of coolant on it. Would make sense that it is running down there toward the square receptor and collecting there. Maybe?

Also, when doing the last heater tee hose this morning I forgot to put the second clamp on before I got it all connected. And now I can’t get the new hose off either the tee or the pipe where it connects. Frustrating. Likely going to order a new hose and cut the just replaced brand new hose off. Argh.!

I see what looks more like gray FIPG in the square gasket... unless that’s how it came from the factory.

End results:

 

[TheBestCow]

Shot of inside the inlet housing where it looks to be bent... but not sure if it was like that. Guessing not, but thought I’d check before another $100 order... and can only put 5 photos per post.

Actually now that I think about it, wouldn’t this cast aluminum be more likely to shatter/break (saw another thread where someone had this o-ring thing break off inside the female receptor, yikes!) instead of bend?

 

[Rick Kane]

Shot of inside the inlet housing where it looks to be bent... but not sure if it was like that. Guessing not, but thought I’d check before another $100 order... and can only put 5 photos per post.
View attachment 2663250
Actually now that I think about it, wouldn’t this cast aluminum be more likely to shatter/break (saw another thread where someone had this o-ring thing break off inside the female receptor, yikes!) instead of bend?

TBC, I just took my water inlet housing off last night for replacement. See the shot inside the same neck - looks like it was ground down intentionally to remove roughness. Based on that, I think some internal roughness (like you see too) is probably the norm.

 

[TheBestCow]

TBC, I just took my water inlet housing off last night for replacement. See the shot inside the same neck - looks like it was ground down intentionally to remove roughness. Based on that, I think some internal roughness (like you see too) is probably the norm.

View attachment 2685352

Thank you very much for the intel! Yea, I've had everything buttoned up and seems to be fine. But good to know!