Khawk2

Hello all,

Recently I have been having to add coolant to the reservoir bottle on my 1997 Grand Cherokee 4.0L I6. It gets to the add level about every six weeks. I drive the my jeep twice a week and mostly highway driving.
The jeep has 166,000 miles on it and starts and runs great.

I'm about to start taking the fan shroud and the other baffles off under the radiator to get a good look at the radiator and hoses. The radiator, water pump and all hoses are about one year old.

I park the jeep in a garage and I do not see any coolant on the floor at any time. The drain from the air conditioning coil is open and draining so if it was a heater core leak, I would expect to see coolant on the floor under the passenger area but no. Also, there is no coolant on the carpet on the passenger side.

Trans fluid level and condition look good so I assume the trans cooler is okay. Engine oil condition and level looks good but I think my problem may be either a head gasket or cracked head.

I have read on the forum about the OEM head cracking problem and cannot recall if the 1997 is in the date range of that problem or if it was corrected by then.

I think the jeep was built in late 1996.

My question is, if I pull the head and find a failed head gasket should I just replace the gasket or should I replace the head to avoid any future problems?

I have also read about an after market head that is a good replacement but cannot find a post that mentions the supplier.

Any suggestions or information would be appreciated.

Sorry for the long post and thanks for reading.

Khawk2

dave1123

First of all that's a small amount of coolant and it's not a blown head gasket or cracked head. Both of those result in significant coolant loss like 2 quarts in a week or more, plus other symptoms like overheating, blowing radiator cores and tanks, and steaming of the tailpipe or dripping coolant out of it. I would be more inclined to think it's the water pump shaft seal. The original water pump has a "weep" hole on the bottom of the bearing that drips coolant down the front of the engine. Replacement pumps now have a "weep chamber" in the same place that holds about a tablespoon of coolant long enough for it to evaporate. When the leak gets large enough, this chamber allows the coolant to drip into the back of the water pump pulley after shutdown and gets thrown off on startup. I discovered this with my 2000 WJ. I had the same mystery coolant loss and only found out about this chamber after starting it up while on the lift to bleed the brakes. When the engine fired up, coolant poured down the front of the engine, then stopped! WTF? In looking thru a catalog for a new pump, the AC Delco listing explained this chamber.

Your 0630 head is not noted for cracking anyway near as bad as the 0331 head introduced in 99-01. I'm not saying it's not cracked, but it's very unlikely. There is a test for a blown head gasket that involves a vial of liquid mounted on a radiator cap that changes color in the presence of combustion gasses. I recommend doing that test before ripping it apart. An easy way to check is to vent the radiator when the engine is cold, reseal the cap, and run the engine for 5 minutes or before it reaches temp. If there is pressure in the radiator with cold coolant, you've got a blown head gasket.

The fix for a cracked head and what I recommend is the "Clearwater" head from Odessa Cylinder Heads of Clearwater, FL. The price is $455 complete with new valves and springs, paid shipping BOTH ways (core return) and guaranteed not to crack for 60 months. It's painted black and ready to mount out of the box. It'll cost you $100 more if the core is not returned in 30 days, but they are pretty lenient about that. It comes with a prepaid shipping label and instructions for it's return. I received mine Fedex Ground in 3 days and the return label was for USPS as scrap metal!

If you park it in a garage, you can check for the weep chamber leakage by placing cardboard under the front end overnight. checking it in the morning, then fire it up, back it out, and checking the cardboard again. If nothing, I figure it's just evaporating from the chamber for now.

Khawk2

dave1123,

Thanks for the reply and the information.

What you are saying makes perfect sense. I did not know about the "weep chamber" and I will concentrate my attention in that direction unless the loss increases and I feel I need to look elsewhere.

I will file the information on the replacement head and hope I do not need to use it.

Thanks again dave.

Cherokee_Mike

I'm also thinking water pump - had a similar problem on my 2000 WJ 4.0 I6 - had to keep topping up the coolant every few weeks - no sign of any coolant loss, just put it down to evaporation.
Then had to start topping up every week, then every few days, then daily.
Checked the water pump pulley - definite movement from side to side & also this caused water to seep out. Seems they can do this for a while before failing suddenly.
One sign to look for is wear on the non-grooved side of the serpentine belt - if it looks a bit ragged this is most likely caused by the water pump pulley running slightly erratically due to the worn bearing.

soulscapex

Great info everyone, i have a 97 GC and i have to add coolant about every few months, i do believe now that its my water pump, i can see some fluid on the top of the hose goin into the pump the metal hose. I was praying it wasnt a blown head gasket

dave1123

One other thing about water pumps on 4.0s. DO NOT buy a water pump with a plastic impeller! When the water pump on my 97 ZJ started sounding noisy, I checked the bearings and found I could move the fan blade tips over 1/2" off center. When I pulled the pump, there was a bright shiny groove worn in the #1 cylinder barrel where the impeller had ridden against it! I went to NAPA and bought their premium pump with a metal impeller. When installing it, I ran all the bolts in finger tight with a socket spinner, then tried to turn the impeller shaft by hand. It wouldn't turn! I took it back to NAPA and checked it against another one and the impeller hadn't been installed on the shaft far enough. The distance was only 1/16" different, but that was enough to let it interfere with the cylinder barrel. SO that means the impeller spins only 1/16" from the cylinder barrel and any looseness in the bearing will allow it to strike metal. This is why plastic impellers shatter! There is NO WAY to get all the pieces out of the water jacket if this happens. Word to the wise!

Khawk2

Thanks again all,

Cherokee Mike, my symptoms are the same as yours were, no sign of coolant loss but tank level drops, refill every few weeks. dave1123, good information on the impellers too. I think I will focus on the water pump unless symptoms change.