Think I may have a head gasket problem...

[thegipper]

I don't think that would work, I believe coolant still passes through the heater core but I'm not positive.

If I do bypass the heater core and try the blue devil, I can still plan on swapping engines at some point. I still have to pull the motor out of my donor rig which I was already planning on doing so I had a spare.

Again, it's not my DD so I am somewhat flexible although time is a rare commodity since I got two little ones.

 

[thegipper]

Is this how I would need to bypass the heater core?

Second picture is of my spare engine.

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[LittleCaesar]

Yes. I would try and take as many pieces with coolant (including the IAC) out of the equation though I have personally never heard of one clogging up due to the use of Blue Devil.

 

[thegipper]

Ok I'll do that. At this point, as long as I don't screw up the heater core (which is why I'll by pass it), I don't have much to lose trying the blue devil.

The truck continues to run excellent so it has to be a small leak.

I'll keep everyone posted.

 

[NegroTundra]

Have you ruled out a leaking injector? I noted a small amount of coolant loss for a number of weeks after my timing belt/water pump replacement, took a while for all the air to be burped.

 

[RonJR]

A another test to run would be to get a pressure tester for the cooling system (available for free rental at Autozone, O'reilly's, etc.) and pump the system up to 20 psi or so when the engine is cold (since that's when you seem to have a leak). Leave it that way for a while, first to see if it holds pressure, and second to see if coolant shows up in the cylinder. Or if it leaks out somewhere else.

 

[thegipper]

Have you ruled out a leaking injector? I noted a small amount of coolant loss for a number of weeks after my timing belt/water pump replacement, took a while for all the air to be burped.

Would a leaking injector wash out the piston/cylinder?

I'm definitely not opposed to doing more tests (leak down, cooling system pressure test etc).

What has me baffled is why the dye test never fails. Maybe it is just an injector if that would wash out the piston. I can maybe try using my other bore camera that hooks up to my phone and take screen shots of the cylinder so you guys can see it.

The amount of coolant loss is super minor. Like, maybe an 1/8" to a 1/4" in the reservoir after a week or so of driving (maybe 100 miles). And I just had the system drained for the timing belt/water pump job a couple weeks ago.

I think I need to do more testing before I make any decision. I'm frustrated to say the least...

 

[thegipper]

Since I love having more tools, I ordered the OTC leak down tester and the Mityvac coolant pressure tester.

Think I should make sure I know whats going on before I do anything too drastic.

 

[RonJR]

Since I love having more tools, I ordered the OTC leak down tester and the Mityvac coolant pressure tester.

See. This isn't a problem, it's an opportunity!

 

[thegipper]

I'm doing my best to have a "the glass is half full" kind of prospective right now....lol

 

[LittleCaesar]

Well, I have always ruled out a leaking injector causing a harsh start up by starting the car/truck for less than 20 seconds, then pulling the plug and seeing if it smells like gas.

Regardless that doesn't explain the coolant loss.

 

[thegipper]

That's the puzzling part. Am I loosing coolant or is it just air escaping from my recent overhaul? I have not lost any amount of coolant for it be a slam dunk, I'm loosing coolant. You'd think if I was loosing coolant (it was being burned) I'd see it on the ground or the dye test would have failed?

Someone else mentioned it took a few weeks for all of the air to escape after they did a TB/WP job.

I'll hopefully know more once I can run some more tests.

 

[thegipper]

Ok so I pulled the cylinder #3 plug again and number 1.

Cylinder #3 is not washed out! It must have been the angle of the camera or the fact that pistons were in different positions when I first looked (using a cheap bore scope).

I just looked with a flashlight and the tops of the pistons on #3 and #1 look identical. Both black and full of carbon. Both spark plugs really do look essentially identical.

I put the bore scope back in and I can read the 5VZ on the top of piston 1 just like I can easily see the A on top of the piston on cylinder #3.

I do not see any coolant pooling up in cylinder 3 or 1 (3 is where I had the misfire).

Dye test again comes back negative. Oil cap and oil on dipstick look normal.



To be continued....

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[Team_Jake]

I literally have the same exact issues going on with mine, cylinder 3 also, for the past 6 months or so. Mine is a DD though, I notice the longer it sits the rougher it starts. Usually it won't start rough unless it's been sitting for longer than 8 hours. When I start it in the morning, it shakes for 4 or 5 seconds. If it sits for a few days it'll run rough for ~10 seconds.

I haven't taken a bore scope down into the cylinder yet, but the spark plug in cylinder 3 looks identical to the other spark plugs. I know it's not a fuel injector issue because I just had mine serviced a couple months ago by witchhunter and nothing changed.

I do have a bore scope though, I think the next thing I'll try is letting it sit for a couple days (when I know it'll start rough), and check inside the cylinder and see if I can find anything that may be leaking into the cylinder. I've done a compression test though and cylinder 3 does have good compression.



I have a gut feeling it might be something really simple (knock on wood), though I'd love to hear from others who might have had similar issues. (I thought I saw a thread by [MENTION=55872]runnyrunnerton[/MENTION] with an identical issue a few years back, maybe you could chime in?)

 

[LittleCaesar]

That's the puzzling part. Am I loosing coolant or is it just air escaping from my recent overhaul? I have not lost any amount of coolant for it be a slam dunk, I'm loosing coolant. You'd think if I was loosing coolant (it was being burned) I'd see it on the ground or the dye test would have failed?

Someone else mentioned it took a few weeks for all of the air to escape after they did a TB/WP job.

I'll hopefully know more once I can run some more tests.

I'd say you are losing coolant via a bad headgasket. When I did my TB/H20 job, I had to fill up the reservoir maybe 1/3 of a quart after 500 miles. I haven't had to touch it since 2011.

Toyotas are hard to purge the air out of regardless, this tool supposedly helps, hope to see less expensive versions this year:
https://store.snapon.com/Cooling-System-Vacuum-Fillers-Kit-Cooling-System-Filler-P889179.aspx

 

[thegipper]

I haven't had to put anywhere near 1/3 quart in yet since I did the TB/WP, I'd say maybe 6 ounces, maybe not even that much. Just took it on a 50 mile drive between yesterday and today and the level didn't change on the reservoir bottle.

tomorrow my Mityvac coolant pressure tester and leak down tester will be here. I wont have time to do the leak down test until Friday but I can probably do the pressure test tomorrow after work.

Whats also weird is for 3 cold starts now, it hasn't run rough once? This was after I initially pulled the #3 plug out and what I noticed was the plug wasn't in there very tight. I know I torqued them when I installed the new plugs but IDK, maybe it loosened up?

I torqued them back down to 14 ft/lbs.

I also put 16oz of seafoam in the gas since I have two 5 gallon cans of it....lol

I'm not sure whats going on. I'm still not convinced I don't have a HG problem, a few more tests and time will tell..

 

[LittleCaesar]

This is about as thorough an explanation to perform a leak down test that I know that exists on the Web. The biggest thing is to make sure the piston is TDC.

Post the results Mike, should be interesting. If you can, do all six cylinders.
https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test

If it turns out to be nothing more than a loose plug, then be happy; No antiseize used I take it....

 

[thegipper]

No antiseize used.

thanks for the link!

 

[diverscale]

such a small ''leak'' would not show on a leakdown test.

Look for the rear heater hoses for a leak, or a waterpump leak. My quick guess is your system still burping and you having a paranoia moment. I don'T clearly remember about my 4runner, but some cars requires quite a long time to burp.

How many miles have you done since changing the coolant? Hit some steep grades up front and idle while in it, that will help burp your system if air is trapped in the HVAC.

 

[etc.]

#metoo

What type of coolant are you using? Red, green or just water?

And FWIW, I have noticed an increase of 4runners for sale on Craigslist because of head gaskets.