could this be the reason for slow overheating?

i just finished installing new head gasket, valve cover gasket, exhaust-intake manifold gasket, water pump, thermostat 160*, thermostat housing, all new hoses, new 3 row radiator from radiator-barn, (2) 10" electric cooling fans (1200-1450cfm each) on the dash my temp reads anywhere from 220-230 and my scan-guage2 it reads 235-250. i was trying to burp the system and bubbles seemed to never stop coming out, after shutting the engine off i notices this..
bubbles were coming out of these two places, i also noticed that the gasket on the thermostat housing was wet from the outside part as you can see on pic 2 (bigger red circle)

Anything that can cause a loss of system pressure will cause the coolant to run at a higher temperature. So, in short, without getting into thermal theory, YES, this can cause a slow overheat.

You could use some thread sealer on spot #1

It looks like your t-stat housing isn't sealing...easy to do. One of the main problems with cracked t-stat housings is mis-alignment of the stat itself when installing. Suggest you re-do the housing IMHO...there should not be any space there between the head and the housing.

The radiator cap is supposed to maintain 16 PSI (I believe). I recently had one that was worn out and wasn't maintaining pressure. It was letting the coolant heat up too much and it was actually overflowing out of the overflow reservior on hot days driving in city type traffic after I would park it. The more pressure that is maintained in the cooling system the cooler it stays via resisting the boiling point. I guess that's why the AC system is extremely pressurized.

I noticed I had this problem when I came back out (from my local city driving when I stopped at a nearby mall) and saw coolant draining down the parking lot. I used some sort of tester for it at a local auto shop. You pump it up (to 16PSI). If it lets air out (you have it submerged in water) then you need a new cap. Mine did it at 9 or 10 PSI. I bought a new cap and have been running cooler since.

If you've been running at those temperatures I'm going to go ahead and say yours is probably worn out. It's a 6 buck replacement so I recommend it.

---"Open" system, NOT older system---

When the system cools down those leaks can let air INTO the top of the engine. Which "kills" the burp and reduces cooling at top of cyl head and overheats.

Fix any leak in cooling system ASAP.
Clue- overnite cooldown -level in Coolant Reserve Tank should go down and level go up with fully warmed engine.
Level should vary about 1/2 inch or so. System should use ONLY a small amount (say <8 oz) added makeup coolant mix in 6 - 12 months.

AFTER all leaks are fixed- Top off radiator THEN PUT THE RADIATOR CAP ON AND DO NOT OPEN CAP AGAIN. IF OPENED -- START OVER.

Level in CRT (Coolant Reserve Tank) at 'full' mark, heater on max heat setting, run engine 5-10 minutes. Engine off, cooldown SEVERAL HOURS,
adding coolant mix to CRT to hold level between 'full' and 'add' marks on tank.

This heat up/cooldown may need to be repeated 2-3 times if lots of air in the system.

If level in CRT is NOT changing = system is not self burping and will tend to overheat problems.

Recheck CRT levels cold/hot for a few days, only takes a few seconds, pop hood, eyeball, close hood. Then each time hood is opened.

Pressurized COOLANT COOLS! AIR DON'T!

A well burped XY is a Happy XY!

Good Luck,
Orange

-Lose the 160* stat.

-Stant super stant 195*F
-or mopar oem (vent at 12 o'clock)
-Stant or mopar regular radiator cap 16 lb.

orange;245340096 [B said:

-Lose the 160* stat. Oops didn't see that[/B]

-Stant super stant 195*F
-or mopar oem (vent at 12 o'clock) I don't think that'll register
-Stant or mopar regular radiator cap 16 lb.

Click to expand...

By "regular" he/we means not one of those caps with the lever release.

Where did you (OP) get the 160 number. This is not a Nissan!

Do a tad more research...please note the statement under my user name!!

OP-Year, etc. ???????


If you are running over about 210*f Your XJ IS OVERHEATING!!!

Normal is 195-210.

continous bubbles is BAD, BAD- could be cyl. head, block, head gasket, etc. etc.

REALLY, REALLY NEED TO FIND OUT EXACTLY WHAT THE PROBLEM IS AND FIX IT, PRONTO!!!

Paradise

roger.

Sry it's a 97 4.0. Ok so I'm gonna change out the radiator cap for a non-lever kind preferably a oem. And change thermostat to stant 195, of course after fixing the leak. Correct?

Also I'm still going to change the thermostat to the recommended, but I just want to understand why a 160 or 180 wouldn't work compared to a 195 please excuse the ignorant question.

TheMule1 said:

Also I'm still going to change the thermostat to the recommended, but I just want to understand why a 160 or 180 wouldn't work compared to a 195 please excuse the ignorant question.

Click to expand...

Nothing ignorant about it ... Theres lots of confusion over thermostat function/operation.

A thermostat sets the minimum engine running temp ..... and has little bearing on the max temps an engine may get to - unless the earlier opening of a lower rated thermostat assists a mediocre designed cooling system prevent temperature spikes ... OR ... the thermostat is faulty and not opening properly.

Various FSMs states that 195* thermostat was fitted in all models ... hence the 195* thermostat becoming a "recommended" thermostat.

Perhaps if the FSM also stated that there was a factory parts listing for a 180* thermostat .... The 195* would not have such a cult following

... And the belief that a 195* thermostat is required for Open/Close Loop fuel management operation helps with the ... "must have a 195* thermostat" line of thought too.

However ..... 160* is unnescessarily low .... and whether your running temp will be that low constantly - depends on weather conditions and radiator efficiency ... as fitting a lower rated thermostat doesnt guarrantee cooler running temps.

Sort out your leaks, replace the radiator cap and see what your running temps are after a couple of startup/cool down bleed cycles .... then experiment with some thermostats in the 180* - 195* range IF you feel a need to - based on your driving requirements and location.


Take note of the comment by orange regarding temps over 210* as "overheating" ..... altho I'm happy to accept the "overheating" temp as 220* ..... Since thats when the factory programmed the aux backup electric fan to activate

Thanks a lot. I'm going to be doing these changes tomorrow. I live in southern tip of Texas, on the border to be exact. that is why I had picked a 160* thermostat, since on a normal day is 90-101*

TheMule1 said:

...why I had picked a 160* thermostat, since on a normal day is 90-101*

Click to expand...

That's the misconception, that a cooler stat will keep your temps down. The thermostat just won't control MAX temps. It's not like a thermostat on the wall, it's pre-set to FULLY OPEN at the specified temp (of the thermostat).

Summer days here can also be in the 95-100 range.


...but it's a dry heat

Ok i now understand how the system works another question is, Are my cfm's good?

TheMule1 said:

Ok i now understand how the system works another question is, Are my cfm's good?

Click to expand...

I doubt that is enough especially if you have an AW4 transmission. Myabe you should look at this ideal alternative.

http://www.dirtboundoffroad.com/featured/xj-%e2%80%93-electric-fan-conversion-kit/

I am using two fans totalling 4,000 CFM. That was years before this unit came on the market.

I've been thinking about selling them and buying dual Taurus fans..