I found this whitish deposit at the rear of the driver's side exhaust/head interface on my 1990 4.0L engine. I'm pretty sure it's caused by a coolant leak, but I can't tell if it's due to a leaking head gasket or if the head is cracked. It's showing from the top of the head, above the gasket level, so I'm thinking it's not the gasket.

Any opinions?

 

is it wet or old dry coolant stain ? Looks dry in the photos.

my 4.0 loves to leak in all the wrong places, for example the radiator has a hex drain plug on the passenger bottom side of radiator that leaks sometimes, otherwise it is dry. I suspect it is an overpressure plug that opens up sometimes??

 

It is dry now, but I know the coolant has been leaking from various high-up places for a while. I've found foamy deposits on the bottom of the intake manifold, so I first replaced the intake gaskets thinking they were the problem. They weren't, as the coolant loss continued. So I tried those block sealants in a bottle, and they would provide only temporary fixes.

This started a couple years ago when I noticed that the heater wasn't putting out hot air. I found a slow leak in one of the heater hoses coming out of the water pump. I read somewhere that if the coolant gets low, the temperature gauge may not show the engine overheating, due to no coolant touching it. So I don't know how long I had been running that way, as I saw no drips on the floor. I may have warped one or both of the heads. The only sure way to know would be to remove them and have them checked. But that's a big effort.

 

removing the heads would be a last resort for me, especially if the engine runs fine.

my Temp switch is like you describe, I just add coolant and the heck with it.

a source of leaks if you have rear heat, is the rear heater valve and hoses, specifically shows up when driving with heater ON, but does not really show when engine is OFF.

 

Just checked the rear heat plumbing, and none of it is leaking.

The initial tell-tale signs were the foamy residues in the lifter valley and under the intake manifold. Coolant loss continued after replacing the intake gaskets. Now this white deposit is further evidence of leaks, and it's looking like a head gasket. I can't really check the compression now as I'm in the process of replacing the transmission, and it and the starter have been removed. It may be time to bite the bullet and pull the heads. Argh...

 

I was lucky that my nephew is a master mechanic for Honda and he replaced the intake gasket. There is a new improved gasket kit for the 4.0

 

Maybe consider having an engine oil analysis done?
If your heads are severely warped and you are losing antifreeze, engine coolant would most likely be present in your combustion chamber and engine oil, so test for it.

And, or since you are in the process of replacing the transmission, and your starter has been removed and you cannot perform a compression test, then do a compression leak down test instead, I actually prefer the leak down test to pin point any potential problem areas, but I agree the compression test is a quicker & easier test to perform.

 

Thanks for the suggestions.

I'm almost certain there's coolant in the oil, as I'm seeing foamy deposits in the bottom side of the lower intake manifold.

Another odd discovery is oil sitting in the intake manifold plenum. I don't know if that comes from the PCV, or yet another leak.

I'm thinking of just replacing the heads, as that would avoid dealing with the possibility of there being cracks in the old heads. Has anyone experience with these:

https://www.ebay.com/itm/17210432306...4AAOSw~bFWGkue

 

Just a note, ebay seller odessa*cylinderhead is actually Clearwater Cylinder Head Inc., I can't tell you if that is good or bad.
Clearwater used to source their heads from Alabama Cylinder Head, and Alabama used MAHLE castings back in the day, Alabama did have a good reputation,
but Alabama Cylinder Head is no longer in business anymore. Pro Maxx Performance Products LLC bought out Alabama Cylinder Head & Patriot Performance.
The cylinder heads in that horrible ebay photo looks like a CIFIC casting to me, so those valve seats should be hardened.

I am sure you have done and are doing a lot of research on this, I spent some time & have tons of notes researching this subject years ago for my 4.0L heads on my Areostar and what I originally wanted to know was how many manufactures of these new head castings there are and who are they, because there are hundreds of suppliers / machine shops for these and based on photos, many different castings were made, so there is not just one supplier. I never found a good answer to this.

Three main issues that I know of with these 4.0L OHV heads are:
1) The stock Ford castings 90TM & 93TM are weak around the intake valve seats and were prone to cracking around the spring pads.
2) The soft iron around the valve seats appeared to not be hardened, and thus the exhaust valve would start to recess into the head, because of the hammer affect of the exhaust valve.
3) Poor lubrication on the upper valve train, so the push rods & rockers tend to see a lot of premature wear.

MAHLE made the original castings to Ford and the later MAHLE castings were more resistant to cracking, but are no longer available.
All the new castings are coming from China or India that I know of nowadays.

I contacted CIFIC years ago and the company stated that their valve seats were hardened steel.
I also emailed Promaxx years ago and they stated that they hardened the valve seats on their own castings.

xlt4wd90, I am positive that I am not telling you anything new that you do not already know, just my 2¢.

 

Thanks Front_Range_Aerostar for your information. I didn't know about the different companies.

Indeed, I did find out the problems you listed. Hopefully the newer castings, even as they're being made in China, have improved the strength around the spring pads and hardened the valve seats. This is why I am avoiding the refurbished heads, which are cheaper.

As to the insufficient lubrication on the rocker arms, I'm not sure what can be done easily as a sure fix. Some aftermarket rocker arms come with slightly larger holes to allow more oil to get to the tips and sockets, but they still don't work as well as the way other pushrod engines do. A possibility is get the complete valve train from Tom Morana, at his price. But I'm hoping that the new rockers will be good enough for a daily driver that doesn't get driven much.

 

Been dragging my @ss on this for months, but finally went through with removing all the parts that were leaking. The engine was literally leaking from top to bottom.

First, the head leak. After pulling the heads, I found this crack between the valve seats on cylinder 6:

There appears to have been a trail of leakage to that rust spot. But I don't know how coolant ended up on the export port as shown in previous pictures.

The top of that piston collected some bilge from sitting so long. Of course this is in the hardest-to-reach cylinder. I will clean it off and check the cylinder for damage.

 

Ouch. Who is going to supply you with a replacement head?

 

mine will be junked before removing the heads.i have to refill the water every other day.i drive thirty miles week days.

 

I had already purchased a set of heads from Odessa/Clearwater. They've been sitting in the back of the van for a couple of months waiting for me to install them. They may have to wait some more, as I'm also dealing with oil leaks on this thing. Cleaning up oily grime is taking a lot of time.

Another disturbing thing is finding a layer of thick gooey sludge on the bottom of the oil pan. Maybe this is due to the coolant leak? I would have expected mayonnaise, but this is like crude oil.

 

Looking at The War from a General's perspective, I've never regretted starting over with something new.
If the @ss tends to be draggin, it is smart to consider a reman that just drops in, drives off.