97 XJ, 200K Miles.

Lately I've noticed the jeep is not keeping coolant in it's system. I've refilled it a few times just to make sure I wasn't crazy or it wasn't a leak in the thermostat housing or something like that. It looks like coolant is coming out of the head gasket right next to the distributor(head 3 or 4).It's always wet in that area. I've looked for cracks in head but haven't seen anything. Turning on the heat today, the air smells like coolant.

Anyways, Some pointers on pinpointing whether it's the gasket or head would be appreciated. It looks like I'll be changing the gasket at minimum and possibly the head.

Lastly, when I do change gasket, would it be bad idea to change lifters, springs, rocker arms, etc? Any advice on what I'm getting myself into would be appreciated!!!

Thanks!

 

If the air smells like coolant, it is most likely the heater core leaking, especially if the one in it is the original. Pull the carpet up under where the passengers feet would go and see if its wet. Not on top but underneath the carpet.

 

Don't forget the XJ's heater fan pulls air from inside the engine compartment and not from the cowl area. Smelling coolant shouldn't be unusual. I never liked that idea anyhow because it's too easy to get exhaust fumes inside the cabin because of it.

If it were my jeep, I'd pull the head, get it reconditioned and checked, see exactly where the gasket is blown and why. Long cylinder heads like those on the 4.0 have a tendency to flex and especially since there's a pair of exhaust valve side-by-side in the center. I strongly feel the major problem with the 0331 head, which you don't have by the way, is the exhaust ports are smaller making those 2 valves retain more heat in the center where they crack. Anyhow, grind the valves, get the head checked, and if it's good, bolt it back together. JMHO however.

 

I'm skeptical that you could get a coolant leak out of the distributor side of the head without it also leaking into the pushrod area and into the oil. You sure it's not just dripping off the lines to the heatercore?

 

Ditto.

Is the oil milky/mocha looking? If not, it is probably not the head gasket over there.

The cabin heater lines are right above that area. If you can't find the leak visually, try UV dye in the coolant.

 

I understand what you're saying. I'll have to check the lines to the heatercore and see if they are dripping down. Also, would it be completely obvious if the oil had coolant in it? I like the guys idea below about checking with UV fluid.

 

Following up to my above post. I'm almost sure the leak is partially in the heater core. I pulled the carpet tonight and it was wet. I'm honestly not suprised it's wet because my floor board plug is currently removed, but the liquid had that yellow tone to it. Unfortunately, it didn't smell much like coolant. So I've got to keep this on the radar and figure out if this is causing the "bead" of coolant at my head gasket.

Lastly, When I posted this post, the Jeep had died several times that day and I'm still having issues with it dying dying now...To the point I'm not driving it. I'm usually good about checking fluids but it was low on oil/coolant. I actually pulled the upper radiator hose and there was not coolant in the housing. I'm guessing it's been out of coolant for a few weeks. I'm also guess the thermostat got overheated and is stuck open...Not sure how this is all tied together, but any help would be appreciated.

Would it be worth sending my oil off to a lab to get tested for presence of coolant?

Thanks!

 

Coolant in the oil should make the oil look frothy chocolate. The engine quitting is very frequently an electrical problem, usually grounding issue.

 

Somebody gave you bad info. If you take them to page J 24-3 of the FSM you can show them where it says " The fresh air ventilating system ( Fig. 3 ) is operated by the air control lever. When the lever is moved to VENT position, outside air form the cowl intake flows into the heater housing. Incoming air is directed into the vehicle interior through vent doors in the housing." A little further down the page is "Fig. 2 Heating System Components" and next page is "Fig. 3 Fresh Air Intake System Components" which shows the ducting and parts.

 

YES, take an oil sample and send it to a Lab such as Blackstone. You have identified several symptoms and it would be helpful to eliminate a few potential causes. For less than $30 oil analysis is money very well spent as you will get data that gives you a much better idea what is going on and if serious engine damage might have occurred. The report will identify even if a small amount of antifreeze and water is present in the oil. I have seen oil that looked fine but the analysis showed the presence of antifreeze. (Note: no antifreeze in the oil does not eliminate a head gasket problem but it seems that most often a bad head or head gasket on the 4.0 contaminates the oil with coolant) In addition you will get info on presence of any excessive wear metals. Oil viscosity will also be tested. If it is off from the weight oil you used, such as 5W-30, it is an indication the oil was severely degraded.

Does your temperature sensor and gauge work? If you had no or very low coolant it is most likely that the engine overheated. This should have indicated on the temp gauge and tghe check engine light would have been on.

 

Thanks everyone for the advice and help. I think I've made some progress and perhaps dodged a $1500 bullet.

So I found coolant under the passenger carpet. This tells me the Heater core is bad. Instead of throwing out a bunch of cash to fix, I went ahead and capped it tonight at the thermostat housing. After I did this, I did a block test(blue dye) to see if there is any type of block/gasket/head leak. This came up negative. I'll try this again in a few days just to confirm accuracy. I'll also take an oil sample on my next oil change and send it off for testing.

For now, I've satisfied why I've been loosing coolant and perhaps, why my engine has been dying the last week. It's been overheating as the oil and coolant has been burning up.

Things should get better for now but my last questions is this: I probably should have done a U hose or 180 hose to the inlet/outlet port on the thermostat housing rather than just putting caps on. Napa didn't have a hose of the type so I just took what I could get so I can drive tomorrow. thoughts?

PS. I live in Texas so not particularly worried about having heat in the winter.

 

You're fine just capping it for now.

 

Performing a block test, or combustion gas test at the radiator cap, was a good move.

I would still be concerned with the issue of it not running correctly if due to overheating. That is not a good sign. If it overheated it would be best to change the oil very soon as high temperature can oxidize oil and produce acids. This reduces the oils ability to properly lubricate and protect critical parts.