3FE puking coolant... from somewhere (1 Viewer)

[ShaneA320]

‘91 FJ 80 with 230k on the meter.

So my 80 started puking coolant from the passenger side the other day. Didn’t notice it until I was driving home and the needle started to move towards the red. My 80 has never had cooling problems, even in 110° desert heat wheeling in sand... and this all happened in a 5 minute drive in town, at night, at 80 degrees outside. Was able to limp it home without the gauge going into the red. Got out to a large puddle under the passenger side.

Basically running down the inlet hose/lower rad hose. Almost no drips on the driver side other than what ran down the steering and came off over there. Huge puddle on the pax side.

Refilled the rad with distilled water (needed almost a gallon and a half) the next day and let it idle back up to temp. No leak. Decided to drive around the block until it started getting hot, 20min later, never got hot

Decided to pull everything off down to the water pump (what a PITA job...) hoping for an obvious source of the leak. That didn’t happen.

Wasn’t much left of the water pump gasket, but even if it was leaking from that, it seems like a leak there would flow towards the driver side, or at least directly below the water pump, with the big hump from the block below it.... I think.

The metal piece that connects the two pieces of the inlet hose looks like it has some old coolant on it and may have been leaking from the top hose. (Pic below) This was also my theory to begin with, and still is for the most part.

The T-stat housing also looks like it was leaking from the picture, but I’m 99% sure that’s from when I pulled it and some residual coolant came out and dried (this was a multi-day project getting everything off)The tstat gasket was in good shape and looked probably somewhat new, at least compared to the water pump gasket.

The plan right now is to replace all the hoses and gaskets (after cleaning all the mating surfaces) then put it all back together and hope it doesn’t leak... I’m just not a huge fan of NOT actually having been able to identify the exact problem.

Also wondering if I should just go ahead and replace the water pump while I’m here.. it turns without a hint of roughness or noise.... but I really don’t want to have to do this job again.

Is there anything I may have overlooked or should delve into a little more?

 

[Rush]

What part of Utah? I'm in SF, grew up down south.
Regarding replacing the pump... when you have the current one out isn't a _bad_ time to do it
Cruiser Outfitters @cruiseroutfit in Draper carries the Aisin OEM water pump, that's where I got mine. (Cruiser Outfitters Part# EGW61180 (Fits 8/87-8/92 FJ62/FJ80, AISIN) - $107.50)

I also hate magically self-healing problems.
I'd suggest pressure testing the rest of the cooling system while you have the hoses off of the pump/tstat housing. I found that a 3/8" -> 1/4" adapter fits into the oil cooler->water pump hose (the one visible below the head's water port in your first photo).
Pressurize the hoses and see if/where you get a leak once you approach 13/14/15 PSI.

That pipe section sure looks leaked-on, but don't rule out your rear heater core's pipes/hoses as a culprit. Those run back past the trans on the passenger side.

 

[ShaneA320]

What part of Utah? I'm in SF, grew up down south.
Regarding replacing the pump... when you have the current one out isn't a _bad_ time to do it
Cruiser Outfitters @cruiseroutfit in Draper carries the Aisin OEM water pump, that's where I got mine. (Cruiser Outfitters Part# EGW61180 (Fits 8/87-8/92 FJ62/FJ80, AISIN) - $107.50)

I also hate magically self-healing problems.
I'd suggest pressure testing the rest of the cooling system while you have the hoses off of the pump/tstat housing. I found that a 3/8" -> 1/4" adapter fits into the oil cooler->water pump hose (the one visible below the head's water port in your first photo).
Pressurize the hoses and see if/where you get a leak once you approach 13/14/15 PSI.

That pipe section sure looks leaked-on, but don't rule out your rear heater core's pipes/hoses as a culprit. Those run back past the trans on the passenger side.

I’m in STG. Went to Cruiser Outfitters for my lockers and a couple other things a few months back, looks like I’ll hit them up again for a water pump. For $100 it’s a no brainer to avoid tearing everything out again.

I’ll have to look into pressure testing the system, I can turn a wrench but I’m pretty inexperienced in any sort of diagnostic aspect along with a personal lack of tool resources.

 

[flintknapper]

Yes, pressure testing it will be the way to go.

 

[Rush]

I’m in STG. Went to Cruiser Outfitters for my lockers and a couple other things a few months back, looks like I’ll hit them up again for a water pump. For $100 it’s a no brainer to avoid tearing everything out again.

I’ll have to look into pressure testing the system, I can turn a wrench but I’m pretty inexperienced in any sort of diagnostic aspect along with a personal lack of tool resources.

You'd notice the leak if it was from the rear heater lines, with no pressure test.
Worth a look.

 

[ppc]

Sounds like your primary issue may have been caused by a stuck thermostat. Secondary would be all the other things you stated above. It is a "cooling system" so everything needs to be addressed. Based upon your description previous maintenance may have been lacking.

 

[ShaneA320]

Sounds like your primary issue may have been caused by a stuck thermostat. Secondary would be all the other things you stated above. It is a "cooling system" so everything needs to be addressed. Based upon your description previous maintenance may have been lacking.

What leads you to believe a stuck thermostat?

After I refilled the coolant, I was able to let the engine idle for about 15min and then drive around for another 15-20min with no sign of getting hot. Right up to operating temp and stayed there. I would think if it was stuck closed then it would have just kept getting hotter.

But yeah, the PO did some cool things with this truck and also a few not-so-cool things. Mostly wiring related though, I haven’t found much that was skimped on maintenance wise.

 

[ppc]

A stuck thermostat can be an intermittent failure. Your description again is very much supportive of that. A thermostat can stick until the temperature rises significantly over normal and eventually overcomes any corrosion, misalignment etc. and then will function somewhat normally for a period of time. Eventually it will stick again and more frequently. The thermostat can be tested in a pan of water on the stove. Monitor with a thermometer to determine start of opening until full open. A replacement is relatively cheap to replace and you have it all opened up anyway.

 

[flintknapper]

A stuck thermostat can be an intermittent failure. Your description again is very much supportive of that. A thermostat can stick until the temperature rises significantly over normal and eventually overcomes any corrosion, misalignment etc. and then will function somewhat normally for a period of time. Eventually it will stick again and more frequently. The thermostat can be tested in a pan of water on the stove. Monitor with a thermometer to determine start of opening until full open. A replacement is relatively cheap to replace and you have it all opened up anyway.

^^^^^

@Shane......I'd listen to this.

 

[bigredmachine]

while your doing the work to the cooling system id replace the rad cap as well

 

[sdb999]

+1 on all the cooling system best practices. I've found many intermittent cooling leaks/weeps by pressure testing the system cold with more than the rated cap. If OEM cap is 13-14 psi, I run it up into the 20 psi range and let it soak there for a bit. With a cold engine you can also hear leaks (sometimes) that may not immediately produce visible coolant. Good luck with it.

 

[ShaneA320]

Pressure tested the system and found one of the heater hoses was indeed bad along with the lower rad hose.

Just about have everything back together... but I broke off my coolant temp sensor while trying to remove a broken bolt in the thermostat housing. The sensor itself was easy to find. But I’m also going to need the connector (with a pigtail) that hooks to the sensor from the harness. The wires literally just broke when I pulled the plug off.

Can’t seem to find the connector anywhere on the internet. Does anyone have a part number or source?

 

[Rush]

Pressure tested the system and found one of the heater hoses was indeed bad along with the lower rad hose.

Just about have everything back together... but I broke off my coolant temp sensor while trying to remove a broken bolt in the thermostat housing. The sensor itself was easy to find. But I’m also going to need the connector (with a pigtail) that hooks to the sensor from the harness. The wires literally just broke when I pulled the plug off.

Can’t seem to find the connector anywhere on the internet. Does anyone have a part number or source?

I think there's a thread about connector rehab or something similar. Repairing connectors, etc. Should discuss standard connectors and how to find them.
But I might be wrong.

 

[NeilC]

Pretty sure I got a replacement connector from rockauto. Under electrical connectors i think. they have good pics. just make sure the slots are in the correct orientation because it was about 2 years ago.

 

[jonheld]

I think there's a thread about connector rehab or something similar. Repairing connectors, etc. Should discuss standard connectors and how to find them.
But I might be wrong.

This is for the 95-97 FZJ80, but many of the connectors are the same across all years.

FAQ - 1995-1997 1FZ-FE FZJ80 OBD2 Main Engine Wiring Harness Connector Information

The following posts are to document the 1FZ-FE US market 80 series 1995-1997 OBD2 main engine wiring harness connectors. While this is not exhaustive in the sense that it covers every single connector, it does cover about 95% of them. The remaining 5% or so are not sourceable outside of the...

forum.ih8mud.com

 

[jonheld]

Also, many connectors have a 5 digit numeric code stamped onto the body. That is the suffix of the part number. The prefix is 90980-.
Individual pins with pigtails are available by searching through the posted PDFs by the suffix number of the connector housing.
The pin/pigtail prefix is 82998-.