Well here is what has been done to this point. Started with no heat and loss of coolant. Determined to be radiator changed radiator, still no heat. Determined may be vapor lock or issue with Thermostat. Changed Thermostat. It was put in backward so had the joy of doing this job twice. Still no heat. Followed this with coolant flush. Lots of crap in the system and then had heat and all appeared to be running well. Fan had numerous cracks in it so decided to tackle the fan. Bought the special wrenches very good investment. Suddenly huge leak behind alternator mount left hand side of engine. 4.0 L by the way before anyone asks. Assumed water pump changed water pump. Discovered impeller was not attached to water pump at all so this was a necessary job. Still have very bad coolant leak behind alternator mount. Hoping this is not head gasket as I have no oil in the water and no water in the oil. Is there a frost plug behind the alternator mount? Does anyone have any suggestions?

 

I remember there is a freeze plug on the front and the back of each head. Is this what you are asking? There might also be some on the front and rear of the engine, even though I cannot say that with certainty.

 

Thanks Copper, with your answer I thought I had to do the work myself and hoped to find a freeze plug on the front of the head. I removed the fan and all necessary pulleys then pulled the alternator and the mount. I see the frost plug but that is not the issue. It appears the thermostat housing connects to the head and is held in place by the valve cover. I have a leak on the left side of the thermostat housing immediately below the valve cover gasket. I assume this is where the coolant would enter the water sleeve of the head. I am not the most mechanical person so if this sounds rediculous I apologize. Any help would be appreciated. I have had suggestions of JB Weld but am a little leary. Any ideas?

 

Please if anyone has any ideas I need help bad?

 

The thermostat housing is not bolted to the head. Therefore, I'm very confused by your description. Is there a way you can snap a picture and post it in your gallery so I can take a look.

 

how is the upper rad hose routed on the 4.0? on the 3.0, its routed right in front of the alternator pulley. mine was cut by the pulley. for the longest time, i was so dumb-founded what the heck is all that coolant coming out of. by the way, my entire alternator area was wet with coolant (but not the portion just behind the alternator fan). i decided to try some rad stop leak. after the van warmed up, there were alot of soapy bubbles coming out around the alternator area. i became even more baffled. after playing around with the hose, i found the cut. it was cut in a position that is not visible, less the hose is pulled to inspect.

sorry for the long story... but if the 4.0's alternator and upper rad hose routes similar to the 3.0... i would check the upper hose thoroughly... flex and squeeze it to see if there's a cut around the pulley area.

 

This is definitely leaking on the thermostat housing where the intake manifold joins the front of the head. Looks like maybe a gasket has blown. Is the intake manifold all one piece or does it come of in two pieces? Will try to post a picture tomorrow. Need daylight to take a pic with the little digital cam I have.

 

Hi Don:

Send me an e-mail. My address is the same as my user name and I'm at yahoo.com

 

Our 4.0 started a MAJOR coolent leak with the same symptoms - first thought to be a freeze plug - turned out to be a blown head gasket - engine had 197k on it - we dropped in a rebuilt engine (I had someone else do it - it's a bit cramped in there for my taste). That fixed the problem

I may be wrong, but I don't think an intake manifold leak would end up near the T-stat housing. Tho I may be wrong .....

Good Luck!!

 

Don:

Since you just replaced the thermostat, and now you say there is a leak out of the thermostat housing, I'm beginning to suspect that the leak does indeed come from there and it was probably caused by a problem in the gasket. What you could do is to borrow or rent a cooling system pump and pressurize the system cold (after filling it up). That would tell you if it's leaking through the hose (very possible) or the the base of the thermostat housing, which has a nipple for upper radiator hose (extremely likely). Both of these are pretty easy fixes, especially now that you have removed the alternator and all the brackets.

 

Copper, sent you the email. Not the best at this stuff would create a gallery and post the picture for all to see if anyone could provide instructions on how to do this.

 

Hi Don:

I got the picture you sent. Unfortunately, the area you are pointing at is where a lot of things converge.

1) It's where the head meets the engine block
2) It's where the intake manifold meets the head.
3) It's also possibly where the timing cover meets the rest.

You probably need to zoom in more in the trouble area and use a little higher resolution. I wasn't able to see much from the picture.

If the leak is coming from the timing cover, it's easy, except for pulling the vibration damper. The damper on the 4.0L can be a real pain in the you-know-what.

If the leak is coming from the intake manifold, it's slightly worse, but doable in a day or two.

If the leak is from the head gasket, that's more like a week's worth of work, but still not too difficult. It might require a lot of back-and-forth online help, but it's doable.

Good luck

 

It is leaking where the intake manifold meets the head. That is a definite.

 

Could be either one then - that's the same place it was leaking when ours blew its head gasket.
Easy way to see if head gasket - not completely definate if not, but definate if bad head gasket:

Remove radiator cap
Fill Coolant to VERY TOP OF filler neck
Start engine and allow to warm up - expanding coolant will probably leak out of top cap - be ready to catch it
if when the thermostat opens the coolant drops in bursts (down-up) - bad HG sorry (head gasket blown between cylinder, water jacket and externally - will not allow for white smoking b/c of pressure from compression stroke)
if coolant is pretty continuous in its drop, then either the HG did not blow for a cylinder but just for coolant, or the intake manifold is leaking.

A compression test may also help.

Hope this helps!

 

This leaks without compression steady stream from where the intake manifold meets the head when filling radiator.