Keep blowing heads, dumping coolant.

[tadjack]

I bought a used cherokee that already had a stroker conversion done to it.

I know that i've got dish shaped pistons, i know they are .030 over bore, i know it has an RV cam of some kind.

I know it is running injectors that look stock, except for the injector on cylinder 1, which looks like a ford injector.

I measured the stroke with the head off, so i assume it's got the 4.2 crank in it, as the stroke was roughly ~3.8


now for the bad, when i got it it kept losing coolant, what i eventually established to be a cracked head as it eventually started misfiring on cylinder one, when i pulled the head there was a crack.

we replaced the head with a junkyard unit from a grand cherokee, head looked fine, if dirty. the number '97' was cast into the metal under the valve cover.

400 miles later, the engine got so hot that it was no longer able to run at all, the temperature warning light never illuminated until after the engine failed and all of the coolant escaped from the engine as steam, then the light came on. the radiator was cold, the engine would not restart.

after a half hour of cooling, the engine was able to restart, but compression is being dumped into the water jacket on the head, as i can see when i run it with the water outlet removed (the coolant starts to bubble and froth, exhaust comes out of the outlet)


my question, is that is this possibly some kind of fluke (the working theory is plugged thermostat from rust in the head''s water jacket, plus a bit of RTV i found in the thermostat) that the second head blew, or could there be something about my block/bottom end that keeps killing heads or causing overheats?


finally, the head bolts i currently have in the engine are four days old, can i re-use them with the new head i ordered?

[vashxj]

I wonder if the block wasn't cleaned after machining and there is some passages being plugged with debris. as for the head bolts this is just me but I always reuse them unless they are stretched or appear damaged

[tadjack]

I wonder if the block wasn't cleaned after machining and there is some passages being plugged with debris. as for the head bolts this is just me but I always reuse them unless they are stretched or appear damaged

the head that was on it when i got it was fine for the first six months i had it, the replacement didn't last a week, but i'm hoping for a fluke unless somebody says something differently.

[Cheromaniac]

Have you ruled out the possibility of a cracked cylinder in the block?

[Muad'Dib]

If you are replacing the head with a junkyard or used head, then at a minimum you should get the Head surface checked for straightness. Otherwise you will likely run into the same issues you are experiencing.

As far as the Head bolts go, only re-use them once. They are a Torque to Yield variant and wont hold as well with more torque cycles.

[tadjack]

If you are replacing the head with a junkyard or used head, then at a minimum you should get the Head surface checked for straightness. Otherwise you will likely run into the same issues you are experiencing.

As far as the Head bolts go, only re-use them once. They are a Torque to Yield variant and wont hold as well with more torque cycles.

I'm going with a brand new head this time.


here's a video https://www.youtube.com/watch?v=Nho6r34 ... e=youtu.be

[tadjack]

Have you ruled out the possibility of a cracked cylinder in the block?

it didn't seem cracked the first time

[SilverXJ]

I know it is running injectors that look stock, except for the injector on cylinder 1, which looks like a ford injector.

Its not a good idea to have different injectors.

400 miles later, the engine got so hot that it was no longer able to run at all, the temperature warning light never illuminated until after the engine failed and all of the coolant escaped from the engine as steam, then the light came on. the radiator was cold, the engine would not restart.

Do you know why it overheated? Did the over heating occur first than the cracked head or the cracked head caused the overheating?

my question, is that is this possibly some kind of fluke (the working theory is plugged thermostat from rust in the head''s water jacket, plus a bit of RTV i found in the thermostat)

Was there enough RTV on the thermostat to block flow?

finally, the head bolts i currently have in the engine are four days old, can i re-use them with the new head i ordered?

There is an on going debate if you can reuse them more than once. I wouldn't. But you will be fine if you only torqued them once. Did you torque them correcly and in sequence?


Once you have the head off I would take a good look at the gasket to see if it failed. As well as take the head to a machine shop to get a once over on it. And put the correct injectors in.

[tadjack]

I know it is running injectors that look stock, except for the injector on cylinder 1, which looks like a ford injector.

Its not a good idea to have different injectors.

400 miles later, the engine got so hot that it was no longer able to run at all, the temperature warning light never illuminated until after the engine failed and all of the coolant escaped from the engine as steam, then the light came on. the radiator was cold, the engine would not restart.

Do you know why it overheated? Did the over heating occur first than the cracked head or the cracked head caused the overheating?

my question, is that is this possibly some kind of fluke (the working theory is plugged thermostat from rust in the head''s water jacket, plus a bit of RTV i found in the thermostat)

Was there enough RTV on the thermostat to block flow?

finally, the head bolts i currently have in the engine are four days old, can i re-use them with the new head i ordered?

There is an on going debate if you can reuse them more than once. I wouldn't. But you will be fine if you only torqued them once. Did you torque them correcly and in sequence?


Once you have the head off I would take a good look at the gasket to see if it failed. As well as take the head to a machine shop to get a once over on it. And put the correct injectors in.

I've got a matched set of injectors from a 97 grand cherokee.

my brother torqued the head bolts, and he didn't torque 11 to 100, went to 110 like the rest of them, but i don't know if that would cause this kind of failure.\


as for the RTV on the thermostat, there was a half moon shape of it, i don't know if that was enough, or that plus the rust, but as i said the radiator was cold and there was no pressure in the system, there was no reading on the dash that the engine was hot.

[tadjack]

this is what the pistons look like. i've replaced the head with a new unit and it runs the best it has yet.


http://img34.imageshack.us/img34/1075/32ge.jpg
http://img21.imageshack.us/img21/985/62sx.jpg
http://img19.imageshack.us/img19/4923/ocfr.jpg
http://img834.imageshack.us/img834/697/9a3w.jpg
http://img703.imageshack.us/img703/4650/c4z9.jpg
http://img42.imageshack.us/img42/9922/rhzl.jpg

[tadjack]

since the head swap, my radiator is not building up pressure.

i put a 180 degree theromstat in it, and i can open the cap while the system is hot and there's not even a hiss.

[woodjeep]

The clean one is where the coolant was leaking...the water turns to steam and blasts all the carbon loose

[tadjack]

figured out where the coolant was going, water pump was finger tight on all four bolts.

[SilverXJ]

Thats definitely not the stock torque spec.. lol

[woodjeep]

you think you would have seen coolant pouring from the front of the motor if only loose bolts