Well here is my problem . My 91 22re started running rough at half throttle . Checked codes and got " lean " tried to clean maf .... Should have searched that one .
Got a new reman afm and truck runs great . Now for the problem when I start in the mornings it fires up ans idles smooth . After about 10 min it starts reving up and down and steaming air the exhaust . Smells like coolant !
When I leave for work it runs great the heat hand never goes past half way but when I get to work and sit the eng off I can hear the coolant boiling ??i have had to add some coolant but not much ? What is wrong
Head gasket cracked head ??
Oil looks good and has not gained or lost any

 

Sounds like a head gasket. Coolant in the oil isn't always the case, just depends where the gasket let go, in your case by the cylinder wall hence smoke coming from the exhaust.

 

Have the radiator checked for gases (exhaust).

 

How do I check for exhaust gas in my radiator

 

Take the radiator cap off and start the engine. If you see small bubbles coming to the top every couple of seconds that's exhaust gasses

 

FWIW, the surging in idle that you experience is often caused by air in the cooling system. In your case, probably exhaust more than "air", but either way it still points to a leaking head gasket.

 

Elaborate how air in the cooling system causes a surging idle.

 

My understanding is that an air bubble against the coolant temperature sensor causes the ECM to fluctuate between "cold engine mode" and "hot engine mode". As you know, the idle speed is higher when the engine is cold.

My old Honda had a small leak in the head gasket and had the same problem with a surging idle. Its still running with the bad head gasket 6 years later though (as I was far too lazy to dig into the engine on a basically-worthless rusted out 1994 Civic).

 

The coolant flows threw the idle control valve..when coolant is cold it gives you your high idle cold and when the coolant gets hot it gives you your regular warmed up idle. If there is air in the idle control valve instead of coolant it doesnt know what to do so your idle with surge up and down.

 

I understand that, I don't think the system will react fast enough to cause a surging idle. Temperature does not change fast. If the IAC is without coolant it will just adjust with air temp. As air is a fluid also

 

Thanks for the help how long will it take me to put a head gasket on ? And is it a very hard job ?
I have tools and average skills

 

It usually takes me 3 days to do a head gasket. You need to have the head checked at a machine shop and that usually takes a day or so. It really isn't hard to do but is just a slow process. First time I just followed the Haynes Manual and it got me thru it. Basic tools and a good torque wrench will get the job done.

While doing the head gasket, is a good time to get the Plenum cleaned up from all the build up from the EGR, get the sensors cleaned and just getting chasing all the threads and cleaning in general will take a lot more time then you might expect.

I cant recall right off, but the torque specs for the head is 60 or 62 and later Toyota changed it to 65 or 68. There was a change and to make you aware of it. Doesn't seem like much but after replacing a head gasket, I have yet to have one to fail with the new specs.

92 Toy has a thread called "Crapped Out, Gotta Start Somewhere" that has a lot of good info in it.

 

i dont completely understand the surging thing myself, but all of my trucks do it when im flushing and changing coolant, until they are completely full.