White smoke...

[nightrider1724]

i had bought a 1994 explorer sport a few months back the guy said it had a blown head gasket replaced it and have been runing it since. its been 4 months now i have put lots of time and money ne brake system new cooling system, new head gasket kit. now just today the truck started to blow white smoke. could the gaskets be bad already??? or could it be some thing else???? i had bought it for 400. should i sell it now since it has almost 200,000 miles on it?

 

[92exp4x4]

When these motors overheat, they almost always warp the heads and blow a head gasket, in that order. Usually the heads will crack at the same time. You most likely blew another gasket because the heads were warped to start with. Also the head bolts must be replaced everytime the heads come off, because they are torque-to-yield bolts. If you reused the head bolts then that may have been part of the problem.

Did you have the heads checked before reinstalling them? If not I would send them out to have them checked. If your heads are good, which chances are they are cracked, have them milled and go from there. But with 220,000 miles, I would rebuild the whole motor, and buy NEW heads.

A compression check will give you your answer. Look to see if you have bubbles in the coolant while doing the test. Any vehicle is worth fixing if you like it enough. I personally love 'em. I got four of them.

Good luck

 

[nitro71]

That's a crapper right there for sure. If you have a local pull n save junk yard you could probably yank some heads for fairly cheap. I'd look for one that's been in a accident as the engine was running right up to the point it hit something. Good luck, on that!

 

[nightrider1724]

i had taken the heads off and found that it was a blown gasket. and sending them to the local shop to have them tested. i had used the same bolts do to the fact i had a buddy say they could be used again. getting new ones this time.


thanks for the tips.

 

[$TheMoneyPit$]

they dont always warp or crack i have a 1992 that has been ran hot way to many times more then i like and smoked bad and then all of a sudden like my thermostat was stuck werid and still running strong

 

[nightrider1724]

well come to find out that the heads was fine i have no clue why the gaskets blow but went down and bought gaskets with a warranty. but if it happens again im not sure what ill do. i had put it all together and shes running strong again!!!!!

 

[$TheMoneyPit$]

cant beat a 4.0 best motor i have had and ive had more then ten ranging from 4.0s all the way up to 460s all motor and nitrous

 

[shaggymane]

well come to find out that the heads was fine i have no clue why the gaskets blow but went down and bought gaskets with a warranty. but if it happens again im not sure what ill do. i had put it all together and shes running strong again!!!!!

Likely it's because you used the same head bolts(the first time). I don't fully understand that *torque to yield* concept but they are use once only. I think it's something a bout they stretch a bit and so can't be used again.

Maybe some one who knows more will enlighten us.:

 

[92exp4x4]

That is exactly it. When tightening a torque to yield bolt, you tighten to a preset torque. Then turn another degree spec.

For example: cylinder head installation 4.0 V6
1. Install heads, torque to 40 ft.lbs in sequence
2. Install intake manifold and tighten bolts to 3-6 ft.lbs
3. Torque head bolts in sequence to 59 ft.lbs
4. Tighten intake bolts in sequence to 6-11 ft.lbs
5. Now turn Head bolts in sequence another 80 to 85 degrees
6. Finish tightening intake bolts sequentially to 11-15 ft.lbs, then again to 15-18 ft. lbs

That final degree turn stretches the bolts to put a pre-load on them. The preload is the force that seals the head gasket. The bolts will actually act as small springs to resist the compression and combustion forces as the motor runs. The pre-load is based on the tensile strength of the steel that the bolts are made from. This stretch happens one time and they do not rebound. Also tightening them more does not accomplish the same load, you must get new ones and I highly recommend motorcraft or high quality parts.

 

[shaggymane]

thanks much.