1996 XJ 2WD, 4.L, inline 6,213k miles, original owner, DD - 195 degree fail safe thermostat regular gasket burped

QUESTION: Do you think the temperature measuring near the thermostat was causing the non- start and then caused the overheating? Temperature readings on dash seem accurate and reasonable.

- Texas August Temps
- Always 210 ish temps never any issues - 195 degree fail safe thermostat ,regular gasket, burped, electric fan tuns on at 220 and when AC is on
PROBLEM: Car non start; applied gas (yes, EFI, I know but I was desperate)got started but would not hold idle with AC on; overheated; replaced thermostat; heater core exchange valve (broke while changing hose)
- Left AC off but continued with hour long trip turning AC on when on highway
- Started to see temps rise but would hold at 220 - 230 with AC off
- terminated trip
- noticed coolant was quite dark and low
- replaced thermostat with another fail safe 195- fail safe worked - stuck open; heater hose sprouted leak after stop and added water to reservoir and radiator

Car still overheating and coolant is getting dirtier

 

I'm not sure how the coolant could be getting dark unless oil or some other containment is getting into it. I'd definitely do a really good flush of the cooling system.

 

Can you elaborate on the not starting thing? Was this one time, does it crank no start when hot and start when cold? Is it always tough to start and sometimes won't?

As much detail as you can on what's happening.

The dark coolant and overheating sounds like a scale/rust buildup issue that is clogging up the radiator.
I would start as Spencer suggested - get a good chemical flush (I'm not sure which, maybe someone can suggest a higher grade one than the standard prestone stuff they sell everywhere you find coolant).

You may need SEVERAL cycles. I'd do three just per the flush instructions on the bottle, if the overheating is still bad, then I'd consider a new radiator. The dark coloring should stop after the 2nd flush for the most part and definitely 3 should get you to a pretty clean coolant state.

I do not believe the starting and overheating are related unless you are showing signs of a bad CPS. Do the flushing right away and give us details on the starting thing so we can advise. Nothing about the starting issue should prevent going ahead with flushing (unless you can't start the engine to run the flush through.. lol)

 

Also it couldn't hurt to pop open the oil cap and take a look at the oil. If you're getting oil in the coolant then there's going to be signs of coolant in the oil... so "milkshake", green tint in the oil, that sort thing.

That level of engine failure isn't something that is typical with the 4.0, so the odds are you're seeing rust/scale.

I would do my best to use distilled water for anything that stays in the system, even if the flush says regular tap... run a low pressure garden hose on both ends of the heater core (take off the hoses at the firewall end) at some point when you're in there to back and fore flush the heater core. Ditch the control valve and put 97+ molded hoses on, it'll surprise you how much it will look like it rolled out of the factory like that.. plug up the vacuum line with some caulk... I like the auto/marine sealant by Dab or Dap... it reeks like rubber glue but works well.

 

Pat and Spencer - thanks you for your replies. It's been very helpful.

Currently in the process of flushing the cooling system a suggested.
Will look at the oil at first daylight.

Starting:
- no issues starting and any type of weather for months on end. So, this was very unusual for there to be a starting issue.
- the car turned over but didn't sound like it had any gas. Said another way, the starter was doing its job very well but the car is just was not starting.
- against my better judgment I applied gas and it started but had trouble holding an idle at around 1000 to 750 RPMs
- drove around the block a couple of times and it would stall as soon as I put the brakes on and brought the car to a stop.
- I was able to get the car started and the idle to be somewhat stable even at a stop, especially if I didn't stop to Long,
- desperate for air conditioning I turned on the air conditioner but could not get the car to stay running at a stop sign with the air conditioner on. It would die as soon as I came to a complete stop.
- Desperate to get to my destination, which was an hour away ,It I would just get the car running on the highway and see about running the air conditioner since I was not going to have to stop.
- that worked for a while and then the engine temperature started to get close to the red mark. I had to shut off the air conditioner in order to get to my destination.
- the car started after I got to the destination it would just run hot. Above the 210 220 mark. If I kept the heater on it would stay around 230 if I was going 75 miles an hour on the highway.

Hope hope that's enough detail on the starting issue. Again, it all started with the car turning over just fine but seem like it was not getting any fuel. I read someplace on the forum that the temperature sensor, if bad, what affect the fuel flow and that's how I connected the two dots but.... It doesn't seem to link with the overheating yeah... Which is when I decided to write my post to ask advice because I can't figure out why it's overheating at the moment given I replaced the thermostat which was in the stuck open position.

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So I'd start with Fuel for the starting and idle issue. It definitely sounds like something where the engine needs more fuel and struggles to get it. A/C adds some load to the engine, so not enough fuel without the extra load, that much worse with it.

Cleaning your TB and IAC are simple, easy and cheap things you can do that could help if you haven't done so recently. You can also look into the "steam cleaning" process (lots of posts on it) to clear carbon build up in the cylinders. I doubt this is going to be the main problem, but it's easy stuff you can do to help establish a solid "base" for diagnostic efforts. Grounds cleaning is also worth doing if you haven't done it in a while.

If you turn the key to "on" and pause a couple seconds before starting (after it's been sitting for a bit), can you hear the pump priming? You aught to.

Certainly a fuel pressure and leak down test are worth trying. I got a serviceable test gauge from Harbor Freight for like $20, but you may find it as a loaner tool if you don't want to buy one.

The '96 was interesting with the fuel pump.. it used a one-off part and there certainly have been instances of folks with 96's having to replace them. So that's a possibility, I'd also see if you have any gas smell in the engine compartment, check all the fuel lines from the tank forward for issues - rotten hose, leaking connectors, etc. Finally, you can always replace the fuel filter if it's been a while in the off chance it is clogging up. It would be worth doing even if it's not the cause, just as routine maintenance.

I get the impression your Jeep has had some negligence in the "routine maintenance" department, so I'd consider going through the list and doing everything that you haven't already done recently. It's worth doing once you've dealt with the pressing items that you need to deal with immediately.

I know I've listed a lot of stuff... fortunately most of these are widely documented, easy and low-to-no cost stuff that has been S.O.P. around here for longer than I've been a member. If anything I mentioned isn't clear, let me know and I can provide more info or links. I don't want to offend your intelligence by sounding like I'm talking down, nor arrogant if you're not familiar, so please, don't hesitate to ask if you're not sure what I'm talking about.

 

No coolant in oil. Thanks for the tip on the control valve.

 

- Not sure on the non starting but I did pull the wires off the sensor on the themostat housing and the engine did not start, check engine light came on
- flushing the system helped but I think the cause of the overhearing was low oil - I normally change the oil 2x a year but with the virus and not driving I did not change it in April. It ended up being 2 quarts low and that seems to be the reason for overheating.
- The no start and idle issues still a mystery

Thanks for all the help

 

take off the radiator cap with engine cool, fill neck to brim, idle engine until warm/hot

If you see bubbles, that will usually be a sign of head gasket failure or cracked head. You may have to add water when thermostat opens

perform a compression check

if pass, flush block with strong products,

lastly replace cooling system components such as WP, radiator, hoses