'91 head gasket/head issues?

[Tony H]

I thought I read that the early Heads had cracking problems.

I have a '91 with 288K on the clock and I am sort of narrowing down the symptoms to bad ignition wires or plugs ( even though they have less then
10K miles on them) or maybe a Head issue. I get intermitent hesitation like water in the gas or a bad Plug or water getting in the cylinder...No steamy exhaust and no sweet smell.
If these did have head gasket issues, was ther e specific cylinder that seemed to be where the gasket would blow out?
I haven't pulled the plugs yet. Oil is clean. minor Anti freeze usage ( but may not be related).

 

[Maniak]

It has been said that the 90TM heads (91/92 explorer motors) are more prone to cracking than the 93TM heads (used in the 93/94 explorer motors). I haven't seen "proof" of it, but when I replaced heads on our old motor ('92 motor) I used 93TM heads and when I rebuilt the '91 motor I had (to put into the '92 truck) I used 93TM heads.

As for where they crack.. common places are between the valves, between water jackets and also on the humps (top of heads) near the ends.

~Mark

 

[Tony H]

These 93TM heads are direct bolt-ons?

I don't know what my issue is yet but just collecting info.

I did the lower intake manifold gasket a while back, I guess I wont have to dig much deeper to get the Heads off.
Heck, I'm hoping I just have a bad insulator on one of my Plugs...

 

[Maniak]

Yes, the 93TM heads are direct replacement. Its the 95TM heads that will make issues (up's the compression if you put them on a 90TM or 93TM style lower end).

~Mark

 

[Tony H]

Thanks. Just looking to do a drop on, get it back on the road fix if I need this done.

This is the family beater but it can't be out of service for long.

Finding these Heads and getting them checked, then spending a day doing the swap would be what I would hope for.

The passenger Head will come off with the AC/Heater crap over there?

 

[Maniak]

The bracket that holds the a/c on is connected to the head, that has to be disconnected.. Same with the bracket for the Alternator and even the power steering bracket.

You don't have to open the a/c or power steering system to remove the heads, just disconnect them and push the away from the heads..

Depending on where you live, the exhaust manifold bolts may be the hardest. I live in southern a/z so I don't have rust issues to worry about (and I have no inner fenderwells so I can just reach over the tires to pull the manifolds).

~Mark

 

[Tony H]

No inner fenderwells. That's cheating

Thanks for the info

 

[DryDog]

I am curious to hear how this turned out.
35K ago I put new heads on my 91 (had coolant running out the tail pipe.) They were new castings from Clearwater Cylinder Head. Complete heads: rocker assy, valves, everything for $185. But after 15K I was getting white smoke at startup - valve guide leaking. And now temp spikes, and coolant overflowing the resevoir, just like when my previous heads had minor cracks. Where did you get your new heads?

 

[Tony H]

After all my worry about the heads. It ended up being a Spark Plug. I just did Plugs and Wires 10000 miles ago so I was ruling those out. Thatis why I had fear of a Bad Head gasket or Head causing this running condition.

One plug had a broken piece of Porcelion on the Center electrode. The Miss was a bad Spark on that cylinder. So far so good.

Sorry to hear about your bad luck with Heads.