External Coolant Leak

[AntleredRuin]

Ok so for the past week (at least), I've had an external coolant leak.
It's not a big leak, so it's easily managed by keeping a couple gallons of distilled water in the truck with me. I'm going through about a water bottle's worth (roughly 24oz) every 2 days.

I'm not too worried about overheating because I always monitor my temps using Torque.

It's definitely external, I can see the puddle under the truck after sitting for a while, and it tastes like coolant.

So the obvious thing to do is get up under the engine and find the leak.
I have not had much time over the past week to do so, though.
I've made a cursory looked under, and while I can't tell where the leak originates from, based on the puddle, it looks like the driver's side, more towards the rear. Obviously, though, a pinprick hole can squirt coolant, so that may not mean much.

From what I can tell, radiator and hoses are fine, the thermostat is tight, and the heater hoses at the center top of the engine bay are tight and dry.

I did change my valve cover gaskets about 4k ago. Not sure if at all related, as I would have notice immediately if I'd missed putting a hose back on. Maybe I split one?

Where would you guys start me looking?
What path does the coolant actually follow?


Edit: I've cleared my cooling system a few times in the 50k since I bought the truck, but haven't replaced any hoses that weren't obviously on their way out.

 

[mtbtim]

Ok so for the past week (at least), I've had an external coolant leak.
It's not a big leak, so it's easily managed by keeping a couple gallons of distilled water in the truck with me. I'm going through about a water bottle's worth (roughly 24oz) every 2 days.

I'm not too worried about overheating because I always monitor my temps using Torque.

It's definitely external, I can see the puddle under the truck after sitting for a while, and it tastes like coolant.

So the obvious thing to do is get up under the engine and find the leak.
I have not had much time over the past week to do so, though.
I've made a cursory looked under, and while I can't tell where the leak originates from, based on the puddle, it looks like the driver's side, more towards the rear. Obviously, though, a pinprick hole can squirt coolant, so that may not mean much.

From what I can tell, radiator and hoses are fine, the thermostat is tight, and the heater hoses at the center top of the engine bay are tight and dry.

I did change my valve cover gaskets about 4k ago. Not sure if at all related, as I would have notice immediately if I'd missed putting a hose back on. Maybe I split one?

Where would you guys start me looking?
What path does the coolant actually follow?


Edit: I've cleared my cooling system a few times in the 50k since I bought the truck, but haven't replaced any hoses that weren't obviously on their way out.

Driver side towards the rear sounds like it could be one of the coolant hoses to the oil cooler. It could be the lower radiator hose. It could be leaking from the neck that houses the thermostat or it could be coming from the water pump itself. I can't think of anything else on that side with coolant flowing through it other than some type of engine block freeze plug which would suck if it was leaking. I guess it could also be a head gasket leak but let's also hope it's not that either.

When doing the valve cover gasket job, did you remove the throttle body? If so, you disconnected the coolant lines under the throttle body. Maybe coolant is pooling on top of the engine and then finally finding a path to the ground on the driver side.

You should get yourself a Cooling System Pressure Tester and see if that helps you locate the leak. [MENTION=69868]LittleCaesar[/MENTION] told me this one is pretty good:

https://www.amazon.com/Mityvac-MV45...ords=Mityvac+Cooling+system+pressure+test+kit

The reviews on this pressure tester is pretty mixed but it's affordable and will probably work fine for you. I haven't purchased one yet so I can't say for sure how well it works. Good luck locating the leak.

 

[AntleredRuin]

Oh I hope it's not a head gasket. Don't see why it would be; I've never seen the temps get over 209, and they usually stay in the 180s. I have an alarm set at 202, just in case. I guess the PO could have overheated it, but surely that issue would have emerged sooner within the past 50k since I bought it.
I'm also reading that HG leaks (usually) only occur when the engine is warm. This is happening when cold, too.

I did remove the TB, yeah. I didn't notice any coolant on top of the engine, but I'll look again.

What does the oil cooler looks like?
Also, another look shows me that the base where the oil filter screws in seems to be collecting a lot of coolant. Obviously drivers side, but that's more towards the front.

I may need to buy that pressure tester, thanks for the link. I just hate buying one-off tools though. Nice to have when you need them, though.

 

[mtbtim]

Oh I hope it's not a head gasket. Don't see why it would be; I've never seen the temps get over 209, and they usually stay in the 180s. I have an alarm set at 202, just in case. I guess the PO could have overheated it, but surely that issue would have emerged sooner within the past 50k since I bought it.
I'm also reading that HG leaks (usually) only occur when the engine is warm. This is happening when cold, too.

I did remove the TB, yeah. I didn't notice any coolant on top of the engine, but I'll look again.

What does the oil cooler looks like?
Also, another look shows me that the base where the oil filter screws in seems to be collecting a lot of coolant. Obviously drivers side, but that's more towards the front.

I may need to buy that pressure tester, thanks for the link. I just hate buying one-off tools though. Nice to have when you need them, though.

If you follow the hose that leaves the water pump housing on the driver side it leads you to the oil cooler. The oil cooler is about the same diameter as the oil filter but it's much shorter, about a 1/2 as tall. It screws into the driver side of the engine block close to the middle. Since you say you are seeing coolant leaking near the oil filter, this is sounding like more and more to be the culprit. If it ends up being that coolant hose, I think I remember people saying they removed the alternator to have a much easier time replacing that hose. The coolant hose in question is about 1" in diameter. When you get your head in there, you'll see the hose I'm talking about. It connects right near the neck that houses the thermostat and then leads to the oil cooler.

 

[AntleredRuin]

If you follow the hose that leaves the water pump housing on the driver side it leads you to the oil cooler. The oil cooler is about the same diameter as the oil filter but it's much shorter, about a 1/2 as tall. It screws into the driver side of the engine block close to the middle. Since you say you are seeing coolant leaking near the oil filter, this is sounding like more and more to be the culprit. If it ends up being that coolant hose, I think I remember people saying they removed the alternator to have a much easier time replacing that hose. The coolant hose in question is about 1" in diameter. When you get your head in there, you'll see the hose I'm talking about. It connects right near the neck that houses the thermostat and then leads to the oil cooler.

OK, thank you for the detailed info. That helps a lot. I'll look soon then report back.

 

[muellernautique]

OK, thank you for the detailed info. That helps a lot. I'll look soon then report back.

i thought this was my problem too, but as of today it started leaking on the other side of the engine as well. so now i'm not too sure. i was hoping it wouldn't be the water pump, but that's what it's looking like to me now.

seems to me though like you have managing it under control. can't let the temp/loss of coolant get away from you while you try to diagnose the problem.

 

[AntleredRuin]

And of course it's been raining for the past few days. Hard to identify a leak when the entire lower half of the engine is constantly wet.
As the weather warms up, though, it seems to be leaking less. Maybe due to old brittle hoses whose cracks show themselves more in the cold weather? I guess I'll find out eventually.

 

[AntleredRuin]

OK yeah, no leak for the past 2 days. What the hell?

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[AntleredRuin]

Or not.
Water pump? The bolts around the tstat are nice and tight.

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[AntleredRuin]

Anyone have advice on the best current TB and WP kit?

My dad works for Firestone and says he can get me a Gates kit for under $200 most likely.
Yay or nay?

 

[mtbtim]

Anyone have advice on the best current TB and WP kit?

My dad works for Firestone and says he can get me a Gates kit for under $200 most likely.
Yay or nay?

The Aircabinman kit on Ebay is probably your best bet. We have a link for this kit in our Timing Belt Video: https://youtu.be/vHC46ypHxWc

If you plan on doing this job yourself, watch Part 2 of Timing Belt video and read the video description and any pinned comments from both videos for additional information and helpful tips.

 

[AntleredRuin]

Perfect, thanks, Tim. I had seen references to that could but couldn't find a current link.
OK ordered. Should be here by this weekend.
I'll definitely watch the video too.

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[AntleredRuin]

So I finally got the TB and WP replaced. (First non-rainy weekend).Took my dad and I about 8 hours total, including going to the store twice and getting lunch. So not too bad.

Broke the crank bolt loose easily with the breaker bar against the frame.

Got it back on with the makeshift steel bar method described here:
https://www.yotatech.com/forums/f116/crankshaft-camshaft-bolt-removal-tool-186081/
It worked wonderfully. Just unbolted the wire harness at the front of the oil pan to give us some room, propped it against the frame, and had at it. Wasn't too hard at all. My only beef with the writeup is it says you need 8x1.25x40mm bolts to hold the crank pully. This is incorrect. They were too short. We had to go buy some 75mm bolts and they worked great.

We had to use a 1/4 drive extension and swivel to get to the TB tensioner from underneath (instead of removing the compressor). A 3/8 drive was too thick.
MBTIM's idea of loosening the tensioner slightly gave us just enough room to slide the belt on easily.

Also, FYI, when renting a torque wrench, stick a socket on it and see if it ratchets well both ways before you leave the store. We had to get a replacement because the whole thing just kept binding up.

It started up fine, no issues. It drives great too, maybe even a little better.
I'm paying attention to the temps, because they seem a solid 10 degrees hotter than they used to be. (Used to be 185-188, now 194-197). I'd assume the t-stat jiggle valve wasn't at 6, but I double checked it.
Maybe its stuck slightly? Maybe an air bubble in the system?
I'll burp it a few times over the next few days. I kept my old, good working t-stat, so I may just trade that back in.

Other than that, all good. No more leaks!

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[LittleCaesar]

Good to hear.

Of all the autos I have worked on in twenty years, this 4runner may be the hardest to burp. Usually running the engine on an incline for at least ten minutes with the heat on is the ticket.

There have been posts saying that it looks as if the old and new T-stats are not 100% the same.

This thing works well:
https://www.tooltopia.com/lisle-246...MImpq85YHn2QIVEVcNCh1MNQ0uEAQYASABEgIdoPD_BwE

 

[AntleredRuin]

Good to hear.

Of all the autos I have worked on in twenty years, this 4runner may be the hardest to burp. Usually running the engine on an incline for at least ten minutes with the heat on is the ticket.

There have been posts saying that it looks as if the old and new T-stats are not 100% the same.

This thing works well:
https://www.tooltopia.com/lisle-246...MImpq85YHn2QIVEVcNCh1MNQ0uEAQYASABEgIdoPD_BwE

OK good deal. I used a flexible funnel to fill the engine first until it started overflowing (about a gallon), then put the hose back on and filled the radiator. I don't doubt this let some air in, as the front was not on a ramp or anything.
I did let it get up to temp (seemingly, at least, as it sat around 188ish until I actually started driving) with the cap off, squeezing the hose for a few minutes.
There are no real inclines around that I'd be allowed to work with (just parking lot entrances), so I may need to borrow a ramp. A flat driveway was a necessity when buying my house, haha.

How are the T-stat's different? Do you mean from the AirCabinMan kit that I ordered?

I may need to get that funnel for next time, thanks for the link.

 

[LittleCaesar]

I know there has been another thread but here is something of notice:
http://www.toyota-4runner.org/3rd-g...tcreeper-stuff-other-weird-random-shit-2.html

If I were just to guess, and that being it without hard data, Toyota changed the design of the T-stat.

Being in Texas I would just run it for 200 miles using the heat or AC, then go back and burp the system again.

If you want to experiment, down the road a month or two from now, put the old T-stat back in the 4runner witht the jiggle valve at 6 o'clock and see if the temps fall.

 

[AntleredRuin]

I know there has been another thread but here is something of notice:
http://www.toyota-4runner.org/3rd-g...tcreeper-stuff-other-weird-random-shit-2.html

If I were just to guess, and that being it without hard data, Toyota changed the design of the T-stat.

Being in Texas I would just run it for 200 miles using the heat or AC, then go back and burp the system again.

If you want to experiment, down the road a month or two from now, put the old T-stat back in the 4runner witht the jiggle valve at 6 o'clock and see if the temps fall.

Ah yes. I did notice that the jiggle on mine is on the inside (like on the black area), not on the outer silver ring with the stamped numbers.
To be fair, though, so is the t-stat that I took out. I know the AirCabinMan t-stat I bought is not OEM, but I thought my original was (no real reason for thinking that, just a hunch). So I guess not, then.
So the design SHOULDN'T make a difference.

Yeah, I'll keep the temps monitored for a while, then burp again.

If not, I'll put the old t-stat back in and see. I'm an expert at this, now.

 

[AntleredRuin]

OK I'm almost positive that it's just a burping issue.
I spent about 20 minutes or so during my lunch break burping it. (with maybe a 10-15deg incline caused by the parking lot drainage system) I just popped the radiator cap and sat back in the driver's seat with it running and the heat on. I got a clear view of the radiator under the hood while it was lifted and saw several bubbles come to the top. I squeezed the lower hose about every 5 minutes or so.

After that I made a spirited 30 minute test drive, and even at stop lights, I never went over 195. So still needs more burping, but on the right track.