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Discussion Starter · #1 · (Edited)
Well, my newish to me 07 FJ does indeed have some kind of problem. It came to me from a friend of a friend with the diagnosis of a blown head gasket on it's second engine (it's at 367k now) The owner was uninterested in doing anything with it and I got it super cheap.

When I first got it I checked for coolant in the oil, oil in the coolant and did a block test as well. All came back looking good with the Blackstone oil analysis showing no sign of coolant in the engine oil. The engine seemed to run well, and I babied it around on short trips for a while, gradually stretching it out to a longer trip of about 45 min out and then back a couple of weekends ago. I wasn't losing any coolant and everything seemed okay.

The coolant that was in it wasn't Toyota pink and was honestly a pretty nasty green/brown color, so last weekend I figured I'd flush the coolant and put the correct fluid in it. I could tell when draining it there was some fibrous material along with some teeny-tiny silver flecks in it that looked like stop leak of one or multiple kinds.

So along with the new coolant, I added some bars leak to replenish what was in there before. (I know there are a lot of mixed opinions on its usage.) I've taken a few short trips around town in the last couple of days and now I'm noticing some wetness and this evening a single drop of my beautiful new pink coolant in a place it shouldn't be.

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So this morning I went and picked up a coolant system pressure tester from the tool rental at Oreilly's. The engine was cold and my initial test seemed positive. It dropped about 1/2 a pound in 35 min and then leveled off. I left it under pressure for most of the day and it stayed right there.

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Just to double check I pressure tested it again and it held perfectly this time for over an hour.

So, I thought there was a chance that with the coolant change, that it just took a bit for the sparkly stuff to seal up what ever slight weep was going on, but wanted to check what happened when things heated up. I tried to get my gopro under the hood, but the plastic mount broke so I used an endoscope to try to capture any leakage in process if it happed to show up again.

This was about 10 minutes into the drive. The first video was so bumpy you really can't see anything, but this is a snippet from when I parked with it running.



Here's a front view illustrating where the coolant is showing up. It's a mashup of a couple of web images. Maybe this will help if it's not clear from the earlier pic where exactly this is happening.

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The image below is not my engine. It's still 100% all put together.

However, I've also been looking at videos and other images to gain a better understanding of how all the parts fit together without tearing everything apart. Just to try to understand a bit better and maybe see where likely failure points might be.

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So it holds pressure and doesn't leak when it cold, but when it heats up it weeps... If it was a gasket failure, would it do this? ...and in the image above, what's the hole marked with red for? There isn't a hole in the gasket or in the block directly under it when assembled.

I'm hoping that someone that is familiar with this engine can help shed some light on what I may have in front of me.

Thanks!
 

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So do you know how many miles on this second engine? Why not go the cheapest route and replace the water pump and associated gasket and seals?
 

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From the first photo I can see the leak is coming from ABOVE the head/block join. One good thing about leaks is they don't flow uphill, so wherever the wetness / built up gunk is, the leak is typically going to be level with it, or above it.

If that points to the water pump, then I'd be with FJC-man and recommend you start with just replacing that part.

By the way, when the pink SLLC (super long life coolant) came along, it could sometimes eat through the FIPG (form in place gasket) used to seal all of the rest of the engine joints. So, Toyota adopted physical gaskets for the water pump and the thermostat housing joins, to eliminate that risk. I wonder (just speculating here) if whoever went over the secondhand motor in your FJ could have replaced the water pump and used FIPG instead of Toyota's gasket there? Just a WAG.


In answer to your other question: yes, it is totally possible for there to be a leak in the cooling system that only shows up when the engine is hot (as the parts expand). I had a leak in an engine like that: pressure test OK, sitting OK, but after a long, hot run, would drip coolant. Drove me nuts until I finally just gave up and replaced the water pump because that was the area it seemed to be coming from. Perfect ever since.
Norm
 

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Discussion Starter · #4 ·
So do you know how many miles on this second engine? Why not go the cheapest route and replace the water pump and associated gasket and seals?
No idea on the mileage on the 2nd engine or even how many years ago it was put in. The only hints I've had was the little bit of info I got when it was offered up to me through a friend... High mileage, second engine, head gasket issue. It was a good enough deal that I didn't blink and had it trailered in from out of state.

The head on the passenger/right side has "2007 Tacoma SR5" written on it in paint pen, so my assumption is that applies to the whole engine and not just the head.

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Regarding the water pump, that's where my thoughts went first as well. After chasing this around, it looks to me like it's coming from an area slightly higher up than that.

One thing that I did when I first got it was run a carfax on it to hopefully find some service records. It does have a history of having water pumps replaced.

The latest only has 18,000 miles on it and was put on 4/23/2020 which is a little under a year ago.
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Prior to that, it has this one listed in 2018. 54k between it and the one above
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This somewhat makes me think they may have been chasing this for awhile and throwing parts at it. However, It could also mean that they didn't put a factory water pump on it and they just aren't lasting very long. (the one that is on it now is 3rd party) (n).

The other possibility is that something just wasn't put back together correctly when they put the last water pump on. I've found several other places on the vehicle with missing fasteners, loose wires, or bolts that were only finger tight. Someone, probably at the tire shop, who worked on it in the past had some oversights on reassembly, or they just didn't care. (n)(n)

Even without the records, it still seems the weep is coming from higher up and further behind the water pump. There is a possibility it could be coming from behind the timing chain cover where the coolant channel runs. I'm not seeing any other wetness along the top of the seam of the water pump at all.

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Back of timing cover... (potentially?)
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Discussion Starter · #5 ·
From the first photo I can see the leak is coming from ABOVE the head/block join. One good thing about leaks is they don't flow uphill, so wherever the wetness / built up gunk is, the leak is typically going to be level with it, or above it.

If that points to the water pump, then I'd be with FJC-man and recommend you start with just replacing that part.
Totally agree with the the idea that it's not going to flow uphill, but I think the head/block join is right in the area of the top of the wetness. To me it looks like where the head/block/timing cover all comes together is right in that area. I'd think that would mean that the coolant to come out here it's either got to be from the head gasket or the back of the timing chain cover.
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By the way, when the pink SLLC (super long life coolant) came along, it could sometimes eat through the FIPG (form in place gasket) used to seal all of the rest of the engine joints. So, Toyota adopted physical gaskets for the water pump and the thermostat housing joins, to eliminate that risk. I wonder (just speculating here) if whoever went over the secondhand motor in your FJ could have replaced the water pump and used FIPG instead of Toyota's gasket there? Just a WAG.
This is really good information!

The water pump (and presumably the gasket) doesn't look like a factory part to me. The factory waterpumps I've seen online have Toyota and Aisn cast into the aluminum. So I'd say it's definitely suspect based on this alone.

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In answer to your other question: yes, it is totally possible for there to be a leak in the cooling system that only shows up when the engine is hot (as the parts expand). I had a leak in an engine like that: pressure test OK, sitting OK, but after a long, hot run, would drip coolant. Drove me nuts until I finally just gave up and replaced the water pump because that was the area it seemed to be coming from. Perfect ever since.
Thanks to both of you guys for the feedback. I really appreciate it.
 

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Discussion Starter · #6 · (Edited)
I'm watching the video from the first link again this morning and am now even suspecting that the leak is coming from further up on the head. It seem like I can see the highlights on the tiny water beads shimmer and change in the area indicated.

If the source of the weep is all the way up here, it's well above the head/block joint.

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I'm going to rig up a different video setup later today and see if I can't capture it better. I'll report later with findings!
 

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Discussion Starter · #8 ·
Easy for the cover to give up the seal on the water channel of the cover. Especially high miles. You can see the recommended Fipg for the cover. On mine, I was generous with 3-5mm bead and some on the head and block.
James, thanks for response what type of FIPG is called for? I'm guessing it's Toyota brand?


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update
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I degreased and power washed the area over lunch.

This evening, I got a good setup going with my GoPro to film the trouble spot while the FJ idled in the drive way. 20 minutes of really boring video with no leakage detected.

I even got in and ran the tac up and held it at 2.5/3 grand for 30/40 seconds a couple of times to try to give it something more than just an idle...

Here's a screen shot from the end of the session.

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Ok, well... maybe it needs more load?

So I took it for an evening drive. Highway, city, and even a short romp through a big vacant lot with some little whoopty-doos.

All in all, about 20 miles of drive it like I stole it. And... we're still dry.

Maybe the sparkly stuff finally took hold? I don't know. 🤷‍♂️. But I'll report back if anything changes.

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