Coolant leak diagnosis (1 Viewer)

[kcjaz]

I have noticed a coolant leak around the transmission after having done a lot of work on my new to me 2015 200. You can see what I've been up to in my Build Thread, but short of it is that I have swapped transmissions and transfer cases and all of the front mounted engine accessories between two rigs. I also swapped the radiators and did the heater tees on my new rig. I'm in the process of shaking things out and have a coolant leak. After the work was done, I have been adding some coolant after running and driving around and am pretty sure at least some of this was just burping air out of the system. Last weekend (a week ago) I drove the rig down to our lake house (~125 miles) where I keep the 200. Prior to leaving I notice some pink on the driveway and the coolant was a little lower than the line on the overflow container. I filled it to the line and drove down to the lake. The next morning, the coolant level was still exactly on the fill line so I thought I was good. This weekend, after the 200 just sat in the garage all week, I noticed a small coolant spot on the floor under the tranny. So I looked under to see where it was coming from and I see coolant on the tranny coming from somewhere above. I took the video below as I slide under the truck:



Typically when you see this, the valley plate leak is the primary suspect. It could of course be that but when we swapped the transmissions we didn't notice and pink stains or evidence of coolant leak on the 2015 tranny. Seems unlikely the engine would develop the valley plate leak the same week we did all this work. I didn't have time today ,before we had to come back home, to look more at this and figure out where its coming from. If not the valley plate leak, what else could it be that I should look for?

 

[GOLIGHTLY]

I have noticed a coolant leak around the transmission after having done a lot of work on my new to me 2015 200. You can see what I've been up to in my Build Thread, but short of it is that I have swapped transmissions and transfer cases and all of the front mounted engine accessories between two rigs. I also swapped the radiators and did the heater tees on my new rig. I'm in the process of shaking things out and have a coolant leak. After the work was done, I have been adding some coolant after running and driving around and am pretty sure at least some of this was just burping air out of the system. Last weekend (a week ago) I drove the rig down to our lake house (~125 miles) where I keep the 200. Prior to leaving I notice some pink on the driveway and the coolant was a little lower than the line on the overflow container. I filled it to the line and drove down to the lake. The next morning, the coolant level was still exactly on the fill line so I thought I was good. This weekend, after the 200 just sat in the garage all week, I noticed a small coolant spot on the floor under the tranny. So I looked under to see where it was coming from and I see coolant on the tranny coming from somewhere above. I took the video below as I slide under the truck:



Typically when you see this, the valley plate leak is the primary suspect. It could of course be that but when we swapped the transmissions we didn't notice and pink stains or evidence of coolant leak on the 2015 tranny. Seems unlikely the engine would develop the valley plate leak the same week we did all this work. I didn't have time today ,before we had to come back home, to look more at this and figure out where it’s coming from. If not the valley plate leak, what else could it be that I should look for?

if it’s valley plate, a borescope makes for a short psychological thriller

Edit: maybe pressure test and get underneath there during the process?

 

[kcjaz]

if it’s valley plate, a borescope makes for a short psychological thriller

Edit: maybe pressure test and get underneath there during the process?

Yes, I'll try a pressure test but the leak seems like its intermittent. I had been adding coolant to burp air over several days and then it seemed all the air was out and the level in the overflow was steady. Then the day I went to drive it down to the lake, I noticed it was 1/2" low and I had some coolant on the driveway. Then after 125 mile drive, it didn't loose any coolant until after it sat for a week. The level is still on the fill line so maybe its just spillage from when we did all the work that got parts wet and getting everything hot during the long drive and letting it set a week got some of it to drip down to the floor. It was a very small spot, like the size of a quarter on the floor. As I'm typing this, I recall I had also noticed at one point that the cap on overflow wasn't on. Maybe the stain on the driveway (before I drove it the 125 miles) was from coolant that had splashed out of the overflow when the cap wasn't on. I don't see how a "splash out" would get coolant on the tranny but it may explain what looked like coolant consumption that I assumed was a leak.

I'll take a better look when I get back down to the lake and do a pressure test then too.

 

[bloc]

I’m not sure whether it would apply to the valley plate sealant but at least in the past it was a well-known phenomenon that a worn water pump could start leaking after it sat dry for a period of time, such as doing work to the car and no coolant in the system for a week. I personally had this happen on a couple customer cars in the 2000’s. I think the idea is the seal rubber has a chance to dry out somewhat then never quite goes back.

Hard to believe this would apply to RTV, but maybe plausible?

 

[GOLIGHTLY]

Yes, I'll try a pressure test but the leak seems like its intermittent. I had been adding coolant to burp air over several days and then it seemed all the air was out and the level in the overflow was steady. Then the day I went to drive it down to the lake, I noticed it was 1/2" low and I had some coolant on the driveway. Then after 125 mile drive, it didn't loose any coolant until after it sat for a week. The level is still on the fill line so maybe its just spillage from when we did all the work that got parts wet and getting everything hot during the long drive and letting it set a week got some of it to drip down to the floor. It was a very small spot, like the size of a quarter on the floor. As I'm typing this, I recall I had also noticed at one point that the cap on overflow wasn't on. Maybe the stain on the driveway (before I drove it the 125 miles) was from coolant that had splashed out of the overflow when the cap wasn't on. I don't see how a "splash out" would get coolant on the tranny but it may explain what looked like coolant consumption that I assumed was a leak.

I'll take a better look when I get back down to the lake and do a pressure test then too.

I’m definitely not the most knowledgeable here, but that valley plate is the closest part of that system to the rear of the block, that isn’t the heater tees right (those are easy enough to inspect visually)? Is your lake house at altitude?

I’d still opt for a borescope and go digging, but I’m sure someone smarter than I will chime in with some better intel.

 

[yOHda]

Replace the clamps on the oil cooler assembly that bolts to the transmission with worm clamps. See if that changes anything.

 

[kcjaz]

Replace the clamps on the oil cooler assembly that bolts to the transmission with worm clamps. See if that changes anything.

Are you talking about this:

The I believe pink is coolant. The fluid in the hose would be transmission fluid right? No coolant goes to the transmission.

 

[GOLIGHTLY]

Are you talking about this:
View attachment 3528110

The I believe pink is coolant. The fluid in the hose would be transmission fluid right? No coolant goes to the transmission.

ATF would be more red/brown than that depending on age, but I guess you could always taste it and confirm. Bon apetit

 

[kcjaz]

ATF would be more red/brown than that depending on age, but I guess you could always taste it and confirm. Bon apetit

It’s not ATF but I’m not going to lick the tranny to verify.

The more I think about it, the more I think this is residue from spilling coolant when we did the heater tees.

 

[bloc]

Are you talking about this:
View attachment 3528110

The I believe pink is coolant. The fluid in the hose would be transmission fluid right? No coolant goes to the transmission.

Nope, that’s a coolant hose. I’m not sure whether it’s just for measurement or some small amount of cooling compared to what the in-radiator and aux ATF coolers do, but that is definitely a coolant hose, not ATF.

That said, worm clamps suck. They chew up the soft rubber and often aren’t totally circular when tight. The factory style spring clamps are superior as long as they are used on original hose with original wall thickness, because they are very sensitive to changes in outer diameter changing clamping force.

 

[yOHda]

Nope, that’s a coolant hose. I’m not sure whether it’s just for measurement or some small amount of cooling compared to what the in-radiator and aux ATF coolers do, but that is definitely a coolant hose, not ATF.

That said, worm clamps suck. They chew up the soft rubber and often aren’t totally circular when tight. The factory style spring clamps are superior as long as they are used on original hose with original wall thickness, because they are very sensitive to changes in outer diameter changing clamping force.

Worm clamps do suck. I had those original spring clamps leak on me though when I did a transmission replacement on my Tundra. Only reason for my suggestion.

@kcjaz most definitely coolant running through the 2 larger hoses, atf runs through the smaller 2 above that.

 

[bloc]

Worm clamps do suck. I had those original spring clamps leak on me though when I did a transmission replacement on my Tundra. Only reason for my suggestion.

@kcjaz most definitely coolant running through the 2 larger hoses, atf runs through the smaller 2 above that.

That’s good useful intel.. they can lose spring tension so it may be good to replace them when disturbed after a long time in service.

 

[GOLIGHTLY]

Worm clamps do suck. I had those original spring clamps leak on me though when I did a transmission replacement on my Tundra. Only reason for my suggestion.

@kcjaz most definitely coolant running through the 2 larger hoses, atf runs through the smaller 2 above that.

Learn something new every day

 

[kcjaz]

Thanks @yOHda and @bloc. For sure learning something new today.

I guess I was just assuming all the tranny cooling was from the actual tranny cooler in front of the radiator. I'm going to first clean up things the best I can and see if I keep getting more leak residue. Also probably do a pressure test. That hose to the cooler does look like it may have leaked. If that is it. I'll replace the hose and the clamps.

This forum is awesome. Thanks again guys.

 

[bloc]

Thanks @yOHda and @bloc. For sure learning something new today.

View attachment 3528207
I guess I was just assuming all the tranny cooling was from the actual tranny cooler in front of the radiator. I'm going to first clean up things the best I can and see if I keep getting more leak residue. Also probably do a pressure test. That hose to the cooler does look like it may have leaked. If that is it. I'll replace the hose and the clamps.

This forum is awesome. Thanks again guys.

Nerd info: in all likelihood more actual trans cooling probably gets done by the ATF cooler within the radiator.. but it just seems crazy we have three coolers. Toyota took this seriously.

 

[linuxgod]

Hose clamps I believe are one time use according to the FSM. Not sure if that’s your leaky spot but despite how silly it might seem I would suggest replacing them if they’re not new

 

[Zill]

I believe the main purpose of that heat exchanger is to allow the transmission to heat up faster with the engine coolant running alongside it (one side is coolant and the other is ATF) with a metal plate blocking them so it doesn’t mix. I don’t think it does much cooling, but it is more so for heating during idle (warm-up).

+1 replace the clamp (and maybe even the hose if you find some damage on the hose itself)

 

[bloc]

That part is number 33490-34010 and appears to be a little plate/plate heat exchanger. With the ATF cooling loop having a thermostat built-in it does make sense toyota would have designed in a way to bring warm coolant to the transmission to provide heat even before the thermostat has opened as @Zill describes. Though toyota technically does call it a Cooler in their parts system. It probably does that as well depending on the difference in temp of ATF/coolant at that point in time.

 

[kcjaz]

You guys have done so well with this thread, take a shot at this one that I noticed while looking at the coolant leak:

Is there something missing here?

What should be bolted to this threaded hole (red arrow)? Passenger side near starter.

forum.ih8mud.com

 

[bloc]

You guys have done so well with this thread, take a shot at this one that I noticed while looking at the coolant leak:

Is there something missing here?

What should be bolted to this threaded hole (red arrow)? Passenger side near starter.

forum.ih8mud.com

Just replied to that thread. Unused on mine.