Moco

So our good neighbor who helps us out a lot with babysitting and whatnot has a 2000 Grand Cherokee 4.0 with about 190K miles on it that her daughter is using. Neighbor just recently moved and the daughter uses the Jeep as a daily driver. The Jeep was dribbling coolant and she asked me to take a look at it and it appears that the seal on the water pump has failed. There are a number of things that need attention on the car, including some badly worn shocks, a VC gasket, a timing cover gasket, and likely the oil pan gasket and RMS.

Since they moved, they live about 90 minutes away now so I told them to bring the jeep up next weekend and leave it for a couple of days and I would knock all the major services out. I've already ordered/received most of the parts, but figured it would be a good idea to join up here an make an introduction in order to get some advice and to have a lifeline in case something goes terribly wrong.

I dont have pictures of the Jeep at the moment, but I will document the progress of my work next weekend. In the mean time, I wanted to say hi and start a thread regarding this mini-project.

I will update later today with a list of parts I've gathered.

dave1123

Welcome to CF, Moco!

I'm basically considered the expert on the 2000 4.0 WJ because I've owned one for almost 100K miles and she's got 209K on her now. She's my DD and the only vehicle I've got.

The big thing I'm going to warn you about right now is when you buy a water pump, make sure it has a metal impeller. When you take it off, you'll see why. The impeller spins about 1/16" from the first cylinder barrel and if the bearings get worn badly, will strike it and shatter if it's plastic. It's near impossible to get all the pieces out of the water jacket. For instance, the NAPA standard pump is plastic and the premium pump is metal. To be sure, open the box and make sure. Another common mistake is the parts guys will sometimes make the mistake of giving you a pump for the v-belt setup. Make sure you specify it's for the serpentine belt because they spin in the opposite direction. Most of the new pumps don't come with the steel pipe for the heater hose, so you'll have to use the old one, but make sure you install it on the pump before you mount it, because you can't turn it after.

It's a good idea to replace all the coolant hoses when you do this to preclude any future leaks or hose failures. Also a new thermostat is a good idea. A 195* is standard. When refilling the coolant, the easiest way to get all the air out of the head is to remove the temperature sender that's screwed into the head right behind the thermostat. Then fill it up until coolant flows out the hole, replace it, and finish filling it. You get 90% of the air out of the entire system that way. If you install the heater hose from the thermostat housing to the lower heater core pipe, most of the air will bleed out naturally.

Oil leaks are not uncommon on the 4.0, however so many at one time is unusual. Make sure the CCV (Crankcase Vent) orifice is not plugged. That's in the elbow of the hose that comes from the rear of the valve cover to the intake manifold. If that's plugged, it can cause pressure to build in the engine and force oil out everywhere, maybe even into the air filter box. Before you condemn the rear main seal, check inside the bellhousing cover to see if the torque converter is wet. If not, the seal is still good.

When replacing the oil pan gasket, there is a trick I've always used on any engine I've ever done. Use sewing thread thru all the bolt holes to hold the gasket in place until you start all the bolts, then break it and pull it out. If you don't get it all, no big deal because the sealer will take care of it. Just tie short pieces thru each hole and knot them.

Any more questions and I'm here to help. Either PM me or write it as a post to share with the rest of us. In my opinion, this engine is the most reliable engine jeep ever used and the basic design started with AMC in 1956! The reason Chrysler dumped it was because of emission standards.

Moco

Dave,

Thanks for the reply. So I actually had a chance to work on the truck a week ago and I replaced the thermostat (165*), radiator hoses, and Water Pump gasket (I misdiagnosed the leak as a bad gasket) in addition to installing new + and - battery terminals.

Here is my parts list for this time around:

So here is a parts list of things I've compiled:

WATER PUMP: Gates 42293
WP INLET TUBE: Dorman 56398
THERMOSTAT HOUSING: Dorman 902-306
SHOCKS: Monroe 37161 and 37162 - not a big fan of Monroe but these are the mid level line and I got them for about $30 a piece at my local store
VC GASKET: Felpro VS50458 R
TIMING COVER GASKET: TC45458
RMS: Felpro BS 40612
OIL PAN GASKET: Felpro OS 34308 R
SPARK PLUGS: NGK 3459
FUEL FILTER: WIX 33929
TIE ROD ENDS: Mevotech Supreme; MES3472, MES3473, MES3474, and MES3475

Moco

Also, regarding the oil pan gasket - thanks for the heads up Dave. I think the Felpro kit I have has those little plastic holder tabs so hopefully, I'll make use of those.

Moco

So I have a couple of questions to direct at the forum, one especially that Im grappling with.

I.) Do I drop the transmission pan and do a fluid drain and fill with filter change? The default assumption for this truck is that it has had little maintenance. Aside from taking the truck around the block once or twice, I havent driven this Jeep and am not sure of the condition of the transmission - Im afraid to kill it with new fluid and filter. At this point, Im going to wait to see when the truck gets here, how the fluid looks on the dipstick. If it looks and smells decent, Im going to pull the pan and replace the filter, fluid, and gasket. If the fluid loos like crap, Im going to hold off and recommend they start saving for a trans. Any thoughts?

II.) In general, I've always viewed timing chains as a 'no service' item. But on this 4.0 motor, Im going to be right there, and theyre so cheap, should I replace the timing chain? Are the chains known to go slack on these engines at <200K miles?

Moco

Last week, I got a chance to look at the Jeep. The complaint was that it was leaking coolant and overheating. There was clear seepage from the thermostat gasket area and the upper radiator hose was torn. I replaced the hoses, thermostat, and water pump gasket (the pump looked good and I was trying to keep costs down). Unfortunately, the seal on the pump had failed as well and I have go back and replace the pump as its leaking significantly.

One interesting that I ran into was that the previous hillbillies that worked on this truck has spliced the electric fan to the truck's harness directly (God knows why - I suspect they either destroyed the connector during removal/install or they had a fan that had the wrong connector for the harness). So to remove the fan, I had to cut the wires connecting it to the harness. To re-install the fan I spliced in some 10 gauge electrical connectors. Theyre not exactly OEM, but should hold up OK:









As you can see, this engine suffers significant oil leaks:




I shouldve replaced the WP when I had the chance:

dave1123

The proper thermostat for this vehicle is a 195*. The normal operating temp should be between 195* and 210* for proper computer mixture control. If it runs below this, the computer stays in "closed loop" mode using preprogrammed information and not using the 02 sensor readings to adjust mixtures, resulting in less-than-optimal mpg. It may even set trouble codes.

Aftermarket fans usually only have 2 black bare wire leads. Polarity is important for direction it spins in. What I did with mine is put insulated spade lug terminals on the wires, one female and one male so if I ever have to remove it, polarity stays the same. There's nothing worse than feeling air blowing out the grill when you're done installing one!

Be aware this engine has the 0331 head on it that tends to crack, although they usually crack around 150K or less. Mine waited until 170K. Watch for coolant in the oil and overheating. During the 02 production run, Chrysler replaced this head with the 0331 "TUPY" head. I replaced mine with a Clearwater heavy-duty new casting for $455.

Draining the trans pan and changing the filter is a good idea. Just remember the pan only holds less than 1/2 of the fluid. I did multiple changes over 200 miles to dilute it enough to say it's all new. There is a reusable sandwich gasket you can get at a dealer. I've used mine 4 times without a leak. DO NOT USE ANYTHING BUT ATF+4. Aftermarket fluids are okay as long as they specify they are ATF+4.

Now is a good time to change the differential and t/case fluids. I used Valvoline 75W-140 synthetic in mine (both) and ATF+4 in the t/case if you've got Selectrac. Quadratrac uses a special fluid.

I think I'm done now, LOL! OH....wait! I use Monroe Sensatrac shocks with good results. I've used Monroe as long as I've had cars. They restore OE ride and are cheap.

Moco

Dave,


Good info. The head does not appear to have cracked. I didn't see any evidence of coolant in the oil. Crossing my fingers that this is the case. The truck hasn't been overheating since I installed the thermostat.


I hear you on the 195* tstat. They are so cheap and since I will be in there again, I'll pick one up and toss it in there.


Also, hear you loud and clear on the ATF +4. Will pick up some quarts prior to the weekend.

dave1123

Be sure to tighten the thermostat bolts evenly, not one,then the other. Tightening the lower bolt before the upper can crack the mounting flange. Ask me how I know that! LOL!

Looking over your pics, it looks like the only maintenance that jeep got was filling the fuel tank! Deplorable!

Moco

Lol. It does have a Jiffy Lube sticker in the windshield.

Surprisingly, knock on wood, that 4.0 really actually runs pretty smooth with only a little chatter from the rockers/valves.

Moco

Getting things staged:

dave1123

From what the rest of it looks like, you may want to check the ball joints and hub bearings. At least for status and possible later replacement. The lower ball joints take all the vehicle weight and they can't be greased.

Moco

Yeah, when it was up here, I pulled the wheels off very quickly to poke around. The BJ's didnt look or feel dangerously worn - so Im going to put that off for the moment. I hate pressing out BJs and dont want to tackle it this weekend anyway. Besides, we're racking up $400 or so in parts already and I want to make sure the engine, cooling system, and integrity of the cylinder head are good to go before she puts more $$$ into it.

Moco

So pulling the valve cover revealed a pleasant surprise - no sludge! I was afraid I would find a bunch of gunk and sludge, but it was very nice and clean:

dave1123

That means 2 things, first the oil was changed regularly, and second the engine was run long enough each time it was started to get up to operating temp and driven for a period long enough to evaporate any water condensation that might have been ingested. Sludge is formed by condensation and carbon byproducts of combustion. It starts off as a white milky deposit and turns black the more carbon is absorbed. In extreme cases it will become solid.

That light tan patina you see on the rockers is just oil film that baked on the metal from heat. That's normal. I noticed it has the injector heat shield on it. That was a factory recall item, so it must have been in for the recall. Mine got new shoulder harness bolts and a PCM update on that recall. They put a sticker on the underside of the hood with the update info.

BTW, 4.0s naturally rattle. It's just their normal trait and nothing to worry about.