Coolant Leak Question

[dbla]

Hey All,

In the continuing saga of not knowing what I don't know I need a little guidance.

After putting nearly 100mi on my FJ62 since replacing the cooling system (water pump, radiator, fan clutch, thermostat, and respective hoses/gaskets) I walked out into the garage to find a decent size puddle of coolant on the floor. Maybe a few cups, but not gallons thank god.

Looking down and crawling underneath the car I don't see an obvious place that the leak is originating from...so I have a few questions before I start tearing it back apart.

The leak was localized under the passenger side front of the LC, the coolant overflow bottle (on the driver side) was empty, but when I opened the radiator cap it was full with visible coolant in the little elbow dealio the cap sits on.

When I drained/flushed the system originally I don't feel super confident that I got all the water out of it before refilling with coolant. So, is there a chance that the "leak" was actually just overflow coming out of the radiator cap? Or is there another explanation? I'm not super familiar with how the radiator cap/overflow bottle setup works so any clarification there could be helpful.

Any ideas?

Thanks in advance,

-Aaron

 

[batthewmrown]

Sounds like the vicinity of the oil cooler if it's passenger side front. Could be bad o-rings?

 

[dbla]

Sounds like the vicinity of the oil cooler if it's passenger side front. Could be bad o-rings?

Oil cooler meaning the A/T cooler deal on the bottom??

 

[2mbb]

There is a heat exchanger on the lower side right (passenger) side of the engine. You should see coolant lines attaching to it. In the picture below you can see seals (o-rings) where the cooler attached to the side of the block. But any of the connecting hosescould be leaking too.

You might be able to rent or borrow a cooling system pressure tester from an auto parts store. It it a hand operated air pump that replaced the radiator cap. You pressurize the system to 10 or 15 psi and look for leaks.

 

[batthewmrown]

View attachment 2059665

Yeah, that little #20 o-ring. Mine were basically flat and cracked from heat exposure. If that looks like where it's coming from, you'll want to replace the copper washer (12) while you're in there. It's a pretty straightforward job. I ran some mineral spirits through my oil cooler just to clean out any gunk that may have accumalated. Should have painted it while I had it out, too. The bare metal surface on it is getting rusty so I'm going to have to pull it again. Anyway, hope that helps.

 

[dbla]

There is a heat exchanger on the lower side right (passenger) side of the engine. You should see coolant lines attaching to it. In the picture below you can see seals (o-rings) where the cooler attached to the side of the block. But any of the connecting hosescould be leaking too.

You might be able to rent or borrow a cooling system pressure tester from an auto parts store. It it a hand operated air pump that replaced the radiator cap. You pressurize the system to 10 or 15 psi and look for leaks.

View attachment 2059665

Yeah, that little #20 o-ring. Mine were basically flat and cracked from heat exposure. If that looks like where it's coming from, you'll want to replace the copper washer (12) while you're in there. It's a pretty straightforward job. I ran some mineral spirits through my oil cooler just to clean out any gunk that may have accumalated. Should have painted it while I had it out, too. The bare metal surface on it is getting rusty so I'm going to have to pull it again. Anyway, hope that helps.

Gotcha seems simple enough. I’ll get under there this weekend and see if that’s where it’s coming from. It looks like the leak is pretty far forward. Maybe parallel with the front passenger wheel if that makes ant difference.

 

[2mbb]

There is a week hole in the water pump pulley shaft boss.

This is where the pressure tester comes in handy.

 

[dbla]

There is a week hole in the water pump pulley shaft boss.

This is where the pressure tester comes in handy.

Yeah I may give that a try. However the water pump is brand new and I don't see any seepage around it.

 

[BlackCat]

Did you replace the radiator cap? It could be boiling over out of the overflow due to a weak cap. My old 62 would do that as well until I replaced the cap and it could build the appropriate pressure to keep the coolant from boiling.

 

[dbla]

Did you replace the radiator cap? It could be boiling over out of the overflow due to a weak cap. My old 62 would do that as well until I replaced the cap and it could build the appropriate pressure to keep the coolant from boiling.

I did, but I think I may do this again... The leak really looks like it's coming from the vicinity of the passenger side, the overflow bottle is on the driver side... Not sure if it could get passed the cap and leak out of the stem?

 

[Gretsch]

water pump, radiator, fan clutch, thermostat, and respective hoses/gaskets

Maybe you could clarify what you mean by "respective hoses/gaskets". Was the radiator cap replaced? Were any of the hoses leading to the oil cooler replaced. If the puddle was on the front of the truck on the passenger side, then I would look more towards the lower radiator hose. These trucks have those intermediate pipes between two hose sections that run coolant to the lower radiator. If you replaced the hose running from the water pump to the intermediate pipe, you may be able to see a trail of dried coolant leading down the pipe to the lower radiator hose. Might just need to tighten the clamps a bit to seal things up. Maybe its simply a loose lower radiator hose clamp. The oil cooler on mine is more towards the middle-rear of the truck. Any leaks there are visible just behind the front axle pinion and not really in what I would consider the front of the truck. When you say front, do you mean like under where the radiator sits, or like under the front axle housing? With a puddle that size its hard for me to visualize it not being obvious where its coming from.

I guess its possible its something to do with the cap, but I would doubt that being the issue, unless its simply not on correctly. If you are replacing the WP then its prolly not a bad idea to replace the radiator cap as well. Its most likely ripe for replacing at this point if original. You should prolly put some coolant in the overflow bottle so that if you still have air in the system the radiator can suck it in as needed and eventually bleed that air out.

I think the oil cooler O-ring is for preventing oil leakage. I don't think the O-rings have anything to do with coolant leakage. Good to replace them but unless you see an oil leak there I wouldn't worry about them.

As others have said a pressure tester would be the fastest and easiest way to figure things out if the coolant trail is not obvious.

 

[BlackCat]

I did, but I think I may do this again... The leak really looks like it's coming from the vicinity of the passenger side, the overflow bottle is on the driver side... Not sure if it could get passed the cap and leak out of the stem?

Well if it’s leaking from the pass side it’s peobably not the overflow. And it’s not the cap that physically leaks, if it doesn’t allow the cooling system to build the proper pressure (generally 13lbs), it’ll allow the coolant to boil. Boiling coolant expands, and over fills the overflow bottle and leaks from there.

 

[dbla]

Maybe you could clarify what you mean by "respective hoses/gaskets". Was the radiator cap replaced? Were any of the hoses leading to the oil cooler replaced. If the puddle was on the front of the truck on the passenger side, then I would look more towards the lower radiator hose. These trucks have those intermediate pipes between two hose sections that run coolant to the lower radiator. If you replaced the hose running from the water pump to the intermediate pipe, you may be able to see a trail of dried coolant leading down the pipe to the lower radiator hose. Might just need to tighten the clamps a bit to seal things up. Maybe its simply a loose lower radiator hose clamp. The oil cooler on mine is more towards the middle-rear of the truck. Any leaks there are visible just behind the front axle pinion and not really in what I would consider the front of the truck. When you say front, do you mean like under where the radiator sits, or like under the front axle housing? With a puddle that size its hard for me to visualize it not being obvious where its coming from.

I guess its possible its something to do with the cap, but I would doubt that being the issue, unless its simply not on correctly. If you are replacing the WP then its prolly not a bad idea to replace the radiator cap as well. Its most likely ripe for replacing at this point if original. You should prolly put some coolant in the overflow bottle so that if you still have air in the system the radiator can suck it in as needed and eventually bleed that air out.

I think the oil cooler O-ring is for preventing oil leakage. I don't think the O-rings have anything to do with coolant leakage. Good to replace them but unless you see an oil leak there I wouldn't worry about them.

As others have said a pressure tester would be the fastest and easiest way to figure things out if the coolant trail is not obvious.

Gotcha, I think a pressure tester is in my future.

To answer some clarifying questions: I did replace the radiator cap. I also replaced the WP Gasket, and Thermostat housing gasket.

I replaced all the hoses included in this kit: Radiator Hoses and Hose Kits ~ FJ60 FJ62

Looking at it now, it doesn't look like the oil cooler hose was replaced (I knew I had to reuse one of the existing hoses when I redid the system).

The origination of the leak (where the water seemed to be pooling under the vehicle) looked to be just next to the passenger side wheel. It then flowed forward a little. I could see a little drop accumulated on the lower radiator hose, but it didn't look like the leak was coming from there. I can spend a little more time under the truck this weekend (maybe with a pressure tester) to see if I can sniff it out.

Thanks for your help.

-a

P.S. This is my first big wrenching project so everything is a learning experience at this point.

 

[Gretsch]

Its hard to tell sometimes where the coolant is coming from when seeing drops on things. With your new fan clutch the fan should be working and can sometimes blow that stuff all around. Good you replaced the radiator cap. My guess is its just a hose somewhere leaking or on crooked. I found you kinda have to make sure they go on straight and the hose touches all the way round whatever its connected to. Then clamp. Someone said here on mud once that clamps are for holding hoses, not sealing them. If you have put the hose on correctly, it should seal pretty well all on its own. Not been my experience exactly but I have seen how easy it is to get a hose on crooked and not be able to see it. Before tearing into anything, maybe go around and ensure your clamps are all tight and you have not forgotten any (I have and spilled coolant all over my newly painted oil cooler because I forgot to clamp one of the hoses.....ruined). The overflow hose is hooked up to the radiator filler neck right?

I would definitely hook up a pressure tester. Fastest way to see what's going on. Its really hard to see leaks on the front of the engine block with everything put back together. Get a light down deep in there when running the pressure test. Look up under the thermostat housing and under the WP. Should be able to do this with engine shut off (i.e reach in with hand and move fan out of the way as needed). And you used sealant on the WP and thermostat gaskets when replacing those items right? I would guess you would see coolant on the front axle somewhere based on where you are seeing coolant on the floor. But instead of guessing, the pressure test should tell you exactly where this went wrong. HTH.

 

[dbla]

Yeah seems like the pressure test is the way to go. I'll keep ya posted, gonna try and get to it this weekend.

 

[DFXR]

This is not specifically helpful, but when I replaced my (leaking) radiator, wp, and fan clutch years ago, I ended up chasing a bunch of little leaks elsewhere in the system afterwards. Rear heater hose, oil cooler, temp sender, etc. With the main weak point fixed - the radiator - a bunch of secondary weak points showed up. Some showed up immediately, others took a little while. Some "presented" a long way from their origin. But none were catastrophic. Good luck!

 

[dbla]

One thing I think I’ve failed to mention is that these leaks seem to occur as the trick is cooling down after being driven. I don’t believe it’s leaking much if any while running. Not sure if that indicates anything.

 

[2mbb]

while the truck is running, the coolant is recirculating through the engine and is generally maintained at a steady temperature--which means a steady pressure. When the truck stops, the water inside the engine gets hotter, as the residual heat from the combustion chambers dissipates. This can increase the pressure inside the cooling system.

Also, as someone else pointed out, as the engine is running the fan is spinning and the truck is moving and a drop-wise leak is much harder to detect because it will shed as a smaller droplet and maybe get blown away.

 

[dbla]

Alright, so none of my local AutoZone's had a pressure tester in stock. I bought a cheapish one off Amazon and figured I'd give it a go.

It arrived today and I pumped the system up to around 15psi then crawled underneath to see if I could see/hear anything. I didn't.

There was a slow pressure loss from the handpump but honestly I can't tell if it's from the system somewhere or the pump's seal around the radiator neck.

I looked at the oil cooler and it didn't look like the source of my leak, there was some coolant residue to the left of it, but that really doesn't look to be the source of it (plus I showered myself with coolant getting the pressure tester off, so it may have come from that).

Any thoughts or next steps? Could this have been the system burping from my recent refill? Could it be overfilled?

 

[Gretsch]

That hose going into the oil cooler looks pretty shot to me. Looks as if whatever oil leak is coating the hose has ruined it. Oil on coolant hoses tends to deteriorate them over time. As to this being the actual source of the coolant leak, I can't be sure from the photo. But since you are replacing hoses, I would replace this one straight away if for no other reason than to rule it out as your source. Your oil cooler is devoid of paint which can be because of hot coolant leaking onto it and removing the paint. Could just be age though as well. As someone said here before, sometimes getting good parts in a system can reveal other weaknesses within the same system. Basically ANY hose on here is ripe for replacing and as far as you have come with this, it would have been prime time to replace all that stuff. The oil cooler seems to be puking oil pretty good so you may consider replacing the O-rings and copper gaskets on it. Be careful removing those mounting bolts on the oil cooler. They are NLA from Toyota and are critical to how the oil cooler works in that they are hollow and are what allows oil to enter and exit the cooler. Also be careful when clamping the hoses on the oil cooler. The hose fittings on the cooler can be crushed by the clamps.

I see what seems to be coolant running along the oil pan. The coolant could be spraying from the oil cooler/oil cooler hose and running along the oil pan and dripping down near the wheel. I am guessing best I can based on your photo. The pressure leak down test should have allowed you to see where the leak is coming from though. I would re-run that until you see coolant dripping out. I would also take a look at the pipe that comes down from the WP into the oil cooler. Hopefully you replaced the little short piece of hose connecting the WP to the pipe when you had everything off. Maybe make sure its camped tight. The coolant layout on an FJ62 is a little different than on the FJ60 so I may be a little off on how its arranged. I am surprised you are not able to see the leak while performing the pressure test.