question on 22re and block seal

[tri5ron]

I have tried just about everything I can think of, and the truck still is under powered, and gets only 17mpg at best.

I have changed the o2 sensors, the catelattic, the TPS, check all vacuum lines, and have taken it to 2 different mechanics.
no body can seem to get it any better.

The compression is a little low, but not much, and is within 5 lbs across all four cylinders.

It has recently developed a new symptom that has me thinking it may be a headgasket starting to go bad.
when it is first started (cold engine), it seems fine. but as it begins the warm up to operating temp, the rpm's begin to "surge" up and down, for about 3 or 4 minutes, then it settles into a acceptable idle speed.

as long as I continue to drive it, the "surge" does not come back.
but if I turn it off for more than 45 minutes to an hour, the process starts over again.
The engine has never been overheated.

I have checked the spark plugs, and they don't look too bad, no excessive fouling, basically a gold to light brown color, no oil burning.

The crankcase oil looks fine, (No chocolate milk), so IF the gasket IS leaking, I do not think it is getting coolant into the oil.

The exhaust pipe is not dripping water, and has no steam in it, BUT it DOES seem to be very "Humid".
Also, when the "surge" is happening, I have had the radiator cap removed to observe the flow of coolant, and it does seem to "Burp" a bit in the radiator. and there has been a minor loss of coolant from time to time.

I tried to do a little test, by hollowing a spark plug out, and welding a air hose fitting to the top. I got the cylinder to TDC, installed my "Test Plug", and hooked up my air hose at 120psi, to see if the radiator would "Burp" again, but it did not "Burp", and there was no appreciable loss of pressure in the cylinder. (so in other words, my little test did'nt tell me anything of value).

I feel that IF the head gasket IS leaking, then it is very slight, and only leaking from a water jacket port, to a cylinder.
(number 3 spark plug does look slightly worse than the others, but nothing too alarming).

I am considering trying one of the Block/headgasket sealers in the radiator ,to see if the humid exhaust disappears, and possibly even have the compression go up a little.
(again, the compression is a bit low, but not bad for 146,000 miles).

I don't normally approve of using any of the block Sealer type products, due to I really have never heard anyone say that they have used it and it works.
I also feel that if it can seal a leaking head gasket, then why wouldn't it clog up the radiator too?

I dont really want to pull the head and change out the head gasket right now, and was wondering what you guys think of the block sealers as a TEMPORARY fix?
Have you ever actually used the stuff ? and had positive results? or negative results?

I do realize that I will probably need to change the head gasket in the future, but right now, it's kind of hard to justify, with fairly good compression, and no coolant in the oil, and only minor loss of coolant.

thanks for any input or advise
btw- it's a 1989 22re engine in a regular toyota truck.

[bradrhale]

how much coolant are you using?? i would not stop at the idea of a possible head gasket leak. might try pressurizing the cooling system to find out exactly where your leak is.
when was the last time you did a full serv tuneup?? might be time if you think that it is underpowered.
you really do not want to change that headgasket. believe me. you do not want to do that. its a pain that noone should have to endure.

[silverhairdeere]

i don't like the block sealers , for a small leack i use alumi-seal one dose lasts me 6 months , if you think there bad on a yota , try a lumina apv with a 3.8 .

shd