1991 heater issue

1991 leaking from were timing cover

new water pump installed, upon test run it appears to be leaking from were timing cover comes in contact with front on engine? Could leak be from the timing cover gasket? Didnt know it came in contact with the coolant.

Or is that part of the head under that? i say the source of leak is in the area at about 10:00 if timing cover face was a clock..

Could have air in the heater hoses, that will block the flow of warm coolant thru the hoses.

When filling the system with coolant remove 1 heater hose at the firewall, this will let all the air out, lift hose up above heater core outlet, when coolant starts to flow out the heater core, lower the hose down and coolant should be coming out of it now as well.
Reattach hose to core.

Now leave rad cap off and start the cold engine, top up coolant, and leave cap off

If coolant starts to overflow out of the cap opening then you have a problem....................
You have a blown head gasket or cracked head.
4.0l engines WILL crack a head if overheated even one time, they have a weak spot in the casing.

What happens with either blown head gasket or cracked head is that it starts off with a small leak, this small leak pumps "air" from a cylinder into the cooling system and that air goes to the high spots in the engine, which is the heads and heater hoses.
This air causes "air dams" blocking coolant flow so engine starts to overheat, reving the engine/water pump can break the air dam and engine will cool off again, but more air is still being pushed in from the leak.

Other sign of this is a Full Overflow tank, or a bubbling overflow tank as the system purges the air being pushed in from the leaking cylinder.
Coolant in the oil and White exhaust can happen at the end stages of a problem like this, once leak is larger

Search on this site for: Glove Test

Definitive FREE test for blown head gasket or cracked head

The heater core on the 1991 is the by-pass for the cooling system, so if it is clogging up, engine will start to overheat.
Remove both heater hoses, at the engine ends.
Point 1 hose down at the ground and hold garden hose against the other hose to Flush the core, and test its flow.
Reverse directions as well, Flush in opposite direction to be sure of good flow.

Crap., I was hoping the answer didn't involve the words cracked or heads or gasket together in the same sentence.,,. i had a feeling something was goin on when the new fan clutch didnt stop the temp fluctuations like i thought i would had.. It runs strong now pretty much but if i switch off after reaching operating temps for couple minutes and then start it right back up it sputters a little for about half a minute-45 sec or till i give it a little gas then it clears up. I bet that water mixing in with the gas on top of the piston heads isnt it,..,Sh&Y!!! I never drive hard never goin 3000rpm,.,.,.Wonder if the quart of none name 10w30 i put in 2 days ago ontop of 5w30 mobil 1 agitated the situation...! as far head jobs go how how hard is it? CAn it be done without taking out the engine? Should both heads be done? Is there an additive i can put in to prolong it some at all?.. OR should i go after a used engine? I aint got much money.//.

Would this be an optimal time to fix taping Lifters?

Not too hard to do the heads in the vehicle, yes you remove both heads and have them cleaned, surface and pressure tested.
I would do the Glove Test first, to either find out it is a cylinder breach or isn't

Could be clogged heater core or rad
You can warm up the engine, and rad, then shut it off and pull back the fan shroud, two bolts at the top.
Run your hand across the rad fins, should be evenly warm, any cold/cool spots are blocked cooling tubes.

pump or head.

No heat because there was no water in heater core. Chked water in rad it was almost empty! I dont know why the truck wasnt running "hot hot" temp gauge reads little above normal as usual even after new fan clutch/themo for months now & it didnt drive or feel like it was hot. I see were the water was comin out from the passenger of water pump some were half way up . I cant see it directly tho. Question is should i assume its the water pump and prepare for that(I hope), or could it still be the head gasket on the front end near pump ?

Would a failing pump explain temp hand fluctuating ?

Didnt do glove test yet, coulnt find nothing for as a balloon..Oil is still simi clear, because its fresh as i been keeping it. It doent "look" like any water is in it & i dint see any sign of oil in the radiator when i topped it off. Fingers crossed.


Let me down easy

If coolant is not changed every 2 years, 3 at the most, the coolant will get acidic and eat away at water pump impeller blades, so they get smaller and circulate less coolant at lower RPMs, so this would fit original problem.
As would steady loss of coolant in general.

4.0l has cast iron heads and an aluminum intake, any time different metals on near each other and water/coolant is flowing by you can get corrosion, happens on boats ALOT.
At passenger side front of lower intake is where coolant flows from the head into the lower intake and it runs across to the other head to drivers side rear of intake.
Passenger side front seems to corrode more often, eats away the gasket and aluminum, if coolant isn't changed every 2 years.
So check that location for leak, it is above the water pump.

Water pump is fairly easy to change on the 4.0l, you can pull it off first and have a look at gasket and impeller, then either get just a new gasket or get new pump and gasket

chessman21 said:

No heat because there was no water in heater core. Chked water in rad it was almost empty! I dont know why the truck wasnt running "hot hot" temp gauge reads little above normal as usual even after new fan clutch/themo for months now & it didnt drive or feel like it was hot. I see were the water was comin out from the passenger of water pump some were half way up . I cant see it directly tho. Question is should i assume its the water pump and prepare for that(I hope), or could it still be the head gasket on the front end near pump ?

Would a failing pump explain temp hand fluctuating ?

Oil is still simi clear, it fresh. It doent "look" like any water is in it & i dint see any sign of oil in the radiator when i topped it off. Fingers crossed.

Let me down easy

Click to expand...

I'd pick up a pressure tester...(do this in a warmer area, I'm in upstate NY and we're getting a bit frozen). Fill the system up and pressure test it. Use a flash light and inspection mirror and see if you can ID where the leak is coming from.

Bear in mind that water pumps have a 'vent/weep' hole. If the bearings or seals act up, it will drain coolant from there. You say the clutch for the fan was changed out? That'd be rare to cause a water pump to fail, but it wouldn't be unheard of while hangin' and bangin' on things to come apart. Might have pushed an already worn out water pump a bit to far.

But this is all a guess on my part.


Just like a guess that very low coolant would make the temp gauge act a bit loopy. It needs a steady constant level to read correctly....just a guess on my part.

S-

Tedybear said:

You say the clutch for the fan was changed out?

Click to expand...

Man thats what im shooting for!, im hoping the change in torque from new fan clutch on the pump shaft/bearings threw something off....


I think at the least "ill" be replacing the pump, thatll be hard enough never the less the heads,

I gotta do what i gotta do or at least try,,


Thx s guys..

Tedybear said:

like a guess.

S-

Click to expand...

sorce of the leak i believe is write around a bolt that is stripped. how am i gonna fix that?

What do you mean when you say the bolt is stripped?

Is the head stripped/rounded so you can't turn it with a wrench?

Or, are the threads in the hole stripped so that a new bolt will not tighten down?

threads in the hole stripped. top left side. I notice the threads half way down the bolt arnt sharp, looks worn? May a new bolt "bite"?

Are all 12 bolts same length that go to this pump? What are the four extra studs that came with pump for?

helicoil insert

i got a tap wrench set and some helicoil inserts. the pump bolt is a #m6 ,, does this mean i use the #7 tap?, the #7 tap and the outer diameter of the helicoil "look" close but i dont know for sure.

Allso i found a nother #6 at lowes thats about four threads longer,, should i try that first? I dont want to bust a water jacket or nothing trying..

I'm not sure the external threads of the helicoil are standard. If you buy the kit, it normally comes with the proper drill and tap. At a minimum, the package will probably tell you what sizes to use. The installation tool is handy also.

Sent from my SM-G920V using Tapatalk

leaking from behind timing chain cover

new water pump installed, upon test run it appears to be leaking from were timing cover comes in contact with front on engine? Could leak be from the timing cover gasket? Didnt know it came in contact with the coolant.

Or is that part of the head under that? i say the source of leak is in the area at about 10:00 if timing cover face was a clock..