87 22re 4runner 4x manual. 65k from last complete rebuild with Engbdr kit and block/head machining. I have been short a quart or two of rad coolant every week or two for a while now with no signs of leakage?? No noticeable poor engine running. BUT, last week blew a heater hose on freeway and over heated pretty good in 108 degree weather at 11pm... found my heater lever is not connected to the heater control valve and the heater control valve plunger siezed. Not sure if it is related but A/C completely stopped working about two weeks prior to the hose bursting, I'm guessing due to exhaust pressure building in system.
With the cap off the radiator, I have tried to burp the system after having it run low then refilling every week or so. Issue is there are a consistent release/ blub, every 20 to 30 sec, of bubbles that come up that doesn't seem to be tied with the flow of coolant with opening or closing of the Tstat. AND the bubbles seem to be never ending. On top of that, the coolant level continues to rise and rise even after Tstat opens to the point I have to stop the burping attempt so it doesnt over flow my burping container....
1. Is there anything other than blown exhaust gas getting in past the HG?
2. Is there any other source air could be getting in to the cooling system without coolant leaking out?
3. ​​If it is the a blown head gasket, can I take my extra head for surfacing then just swap cam and rockers over?
4. How do you test the head to see how many times it has be resurfaced and how does the head thickness correlate to choosing the proper HG thickness?
5. How do you test the water pump to make sure its moving coolant properly.

Just want to diagnose/test any other conceivable thing before taking the head off. Thx.

 

Possibilities:
1) Leaks where it's hot enough so it vaporizes and does not leave an obvious trace
2)Possibly burning coolant so it also vaporizes without trace.
3) Exhaust gas pressurizing cooling system thru bad HG or cracked block.

I suspected bad HG when mine was running hot and at one point coolant was bubbling with radiator cap off. I'm glad I did old-fashioned glove inflation test here and old-fashioned burping, before some incompetent/dishonest shop charged me to replace a GOOD head gasket. Turns out bubbling was from air in system and running hot was from defective temp sender.

 

If it's not leaking, then it's going out the exhaust...like mine did. Mine never did run hot. Just consumed antifreeze and no leaks. Ran it like that until it contaminated the oxygen sensor.

 

so is there any other conseavable was for exhaust gas to get into coolant?

 

If not bad HG, cracked block?

 

ooh, sorry I asked.... Ok, anyone know how measure a head "height" I guess it would be? I know when I rebuilt this I took it to a machine shop and had it resurfaced, I don't know if it had been before, they said it was good last time, but how many resurfacings can be done and how do hou measure to see if you are there?

 

Read the installation tip.

https://www.cloyes.com/toyota-2-4l-22r-clo-9-4148s/

Can't find the exact picture of how to measure the cylinder head, but I saw one floating around the net back years ago.

 

Thanks for trying, still looking for a good machine shop. Put my trust in them I guess.
​​​Anyone see an issue with having my extra head surfaced then just swapping the cam and rockers? As long as the machine shop passes all the measurement pressure tests?

 

I think LCE May have some head height specs. Iirc, I think it was 3.13” from bottom of 1/2 moon/cam journal to head surface. But check that.
as a rule of thumb, we never had the machine shop go more than .010” machining. If you warped the surface than you also warped the top, which means the cam journals are off the same amount. You could always take more off than .010” off the head and use a metal shim to compensate, but you need to have the cam journals line honed so the cam doesn’t bind.
i see no issue in transferring a cam and rockers. Better to use used OEM than new Chinese aftermarket

 

I ran into similar issue for years. I thought it was the head gasket a but could never find the problem. When I pulled the head I realized that there were cracks between each valve seat that was allowing coolant to intermittently leak by. It also caused the heater core to fill with exhaust gases and air locked it as well as dumping oil into the coolant system which clogged the radiator tubes.

Pull your plugs and get a bore scope to look up at the valve seats. You'll need one with a good light as some are pretty small and hard to see even with the head off.