mysterious coolant loss

[DaveKerwin]

Hey guys, 01 T4R, 3.4 92k miles.

Every two or three months my resuivor goes empty. I can see no drips or visible leaks on any of the coolant lines/hoses.

No funny idle or misfire that I have been able to detect either.

Is there a way that these motors typically lose coolant? What would you suggest as my next step to figure this out?

TIA

 

[drmorbius]

Hey guys, 01 T4R, 3.4 92k miles.

Every two or three months my resuivor goes empty. I can see no drips or visible leaks on any of the coolant lines/hoses.

No funny idle or misfire that I have been able to detect either.

Is there a way that these motors typically lose coolant? What would you suggest as my next step to figure this out?

TIA

Check your engine oil, if it looks like a milkshake you have a blown head gasket.

 

[DaveKerwin]

Re: Re: mysterious coolant loss

Check your engine oil, if it looks like a milkshake you have a blown head gasket.

no coolant in crankcase.

are these motors prone to head gasket or other gasket issues?

Could it be going only into the combustion chamber? I don't see any white smoke at tail pipe either.

The leak is slow, and so far no signs of where it is going, that is why I am confused.

Thanks

 

[Charlee78]

Did you had a look around the damper pulley? Near the thermostat, that's where you can see if the water pump is leaking. If it's auto, you might want to check your tranny oil level/color, I've seen a couple of transmission coolers with cracked tanks.

 

[DaveKerwin]

Did you had a look around the damper pulley? Near the thermostat, that's where you can see if the water pump is leaking. If it's auto, you might want to check your tranny oil level/color, I've seen a couple of transmission coolers with cracked tanks.

Is the damper pulley just below that plastic overlay on the front of the motor? Should I remove anything to inspect or just look around?

It is auto. Tranny fluid was a little dark, just had it drained and filled 1000 miles ago (not because of this issue, just because it was old fluid, probably factory fluid).

Mine does have a factory hitch, and I assume that means I have a trans cooler, is that always the case? If so, it must be built into the radiator, because I did not notice a separate cooler.

When I hit 100k I planned on doing the whole front of the motor replacement parts like chain, belts, hoses, water pump, etc. Perhaps it would make sense to do it sooner.

Any further thoughts?

 

[One_96TR4]

If you have rear heat there could be a small leak in the lines running under the truck. I had this issue and never noticed anything on the floor pooling but the lines leaked very slowly. I guess over the years rust just got to them.

 

[shawnstcyr]

Mine does this, too. I have never discovered a leak. Plugs and all fluids look great. I just add a little every 4 months. I figure it may be just minor evaporation from the reservoir.

 

[pat161]

Considering this has been ongoing I would say you are safe from either a blown HG or a ruptured tranny cooler, you would have had significant issues by now. To answer 2 questions, no, HG leaks are not common on the 3.4, some of the very early ones did leak, but not the same issue as the 3.0 and not prevalent at all. All auto 4Runners come with a tranny cooler whether you have the hitch or not, Toyota never offered a standard tranny cooler which is separate from the readiator and looks like a small radiator. Toyota chose, like many other vehicles, to put the cooler inside the radiator, some have had this internal cooler rupture causing coolant and tranny fluid to become quite intimate in the wrong setting. I would say you are either slowly leaking from a hose somewhere, perhaps the rear heat, or at the water pump. As you are at 92k you are due for your service now, the reccomended interval on the T-belt is 90k not 100k, certainly no big deal but if I were you I would just open it up now. I did my 02 at about 84k as my water pump was leaking visually, there was red caked up coolant visible on the front of the block.

 

[DaveKerwin]

If you have rear heat there could be a small leak in the lines running under the truck. I had this issue and never noticed anything on the floor pooling but the lines leaked very slowly. I guess over the years rust just got to them.

I do have rear heat, good call. So you think leak could be under truck OR in the cabin? I will look into this, thanks.

 

[Charlee78]

If your rear heater is leaking, it will be under the vehicle (not inside the cabin), the lines are just beside the frame on the right side of the truck.