What's up guys,

Took the 96 out today to get her juices flowing. She isn't my DD so I take her out every couple of weeks or so. She did fine all day with the exception of the oil pressure. Most of the day it stayed pegged because the connector for the sensor is fouled up and I haven't changed it. Right before I got to my destination however, it was reading around 40 at cruising speed but would drop to 20 when I decelerated and came to a complete stop.
I'm unsure what to make of that. Could it just be the sensor or may I have a problem with losing my oil? Haven't noticed any leaks or anything but was just wondering. Probably a good idea to just change the sensor and be done with it.

On to the next problem. Almost home now and decided to hit the mountain road just to test the 4x4 and take in some sights. She stayed normal temp all the way down the highway coming home but halfway up the mountain she over heats.


She got up to about 225* so I cut her off to cool down and poke around under the hood. Heard what sounded like air pressure seeping out from around the thermostat housing. Both coolant tubes HOT and had quite a bit of pressure. The thermostat clearly wasn't opened but how is that possible considering she was doing fine for about 45 minutes on the highway? Could it be that the uphill terrain was just much more work and caused her to get hotter? What do yall think?

One more question and help me with your opinions on this one as well. Engine cooled down so I took the radiator cap off to top of the fluid. When I took it off the fluid is nasty brown rusty ****. Definitely needs a flush! But is that all it is? Could someone have used some kind of sealant in the radiator as a temporary fix to a leak or gasket in the engine? I've seen my father do this to an old 4.3 he had some years ago is why I wonder this. What do you guys think?





Stuck my finger down in the top and felt this crap settled where the pipe elbows into the radiator. What's the damage? or will a simple flush fix the problems?




At the moment, I'm going to change the thermostat, flush the radiator, and change the oil sending unit. Anything you guys might add to that from what you see? Any help is appreciated guys!

 

Flushing the radiator is a good place to start. Be sure to isolate it from your heater core (which you will probably also want to flush.) Possibly changing your radiator hoses, radiator cap, t-stat wouldn't be a bad idea either.

 

Oil pressure is normal. Goes up while driving and drops while stopped.

T-Stat could be going bad and only been partially opened during normal driving. Once you hit the mountains the engine could have heated up beyond what the small opening was capable of cooling. There is also a lot of cool air flowing in while at highway speeds as opposed to driving up a mountain at a slower pace.

Brown stuff could be a sealant of sorts. You'll need multiple flushes to get it all out must likely. Take a hose and run water through the system to clean it all out first then add 50/50 coolant in it. Do you have good heat? If not, your heater core could be clogged up from that gunk too.

 

Thanks man, didn't even think about the heater core!

Good to know about the oil pressure. Had me worried for a minute. Still need to change the sensor because it pegs at start up every time. Yeah when I change it I will test it on the stove or something. You are probably right. Yeah the heat is great! Sometimes too good. PO said he replaced the heater core but you know how that goes. I'll just have to see when I flush them separately. I appreciate the advice guys!

 

Looks like quite a while of owner neglect. Once that mess is flushed out of the 3 main areas (motor/head, rad, heater core), the fresh coolant level/color should be checked frequently (cold motor, remove the new rad cap) because it will probably turn rusty/nasty quickly again. Drain it/flush it/refill with fresh again. Takes a while/several drain/refills to clean up years of owner neglect in a iron motor. If it continues to overheat, time to start replacing cooling system components.

 

Cool. I was just worried that it was sealant which can hide bigger problems. When I do the flush, just use the garden hose? No special engine cleaner/rust remover stuff from the auto shop?

 

I would strongly recommend u flush the 3 areas separate of each other. Remove both hoses from the t-stat cover, the heater hose from the water pump and the lower rad hose from the water pump. Stick the garden hose in either heater hose, then in the heater hose nipple on the stat cover and last in the top rad hose. Flush, flush, flush. Check fresh coolant frequently.....it will likely turn rusty quickly again. Inspect/repeat frequently. Drain/refill at 1st sign of coolant turning rusty.

 

Appreciate the advice. Never had this problem before because I've never owned a vehicle with an iron block. Only Hondas until I got the Jeep.

 

Seeing neglect like that makes me sad.

Hey djb, now would be a good time to show him what it SHOULD look like underneath the rad cap

 

If hear air pressure seeping through thermostat housing you need to reseal the housing with a new gasket or rtv. My cherokee previously overheated last week. Radiator was all gummed up. I replaced radiator and my waterpump, and thermostat, and she runs beautifully now. And if you are going to flush the radiator, run a pressure check to see if it is leaking anywhere first. If it is leaking it is not worth flushing it right now. Just buy a new radiator

 

I removed the thermostat and it came out in 3 pieces...

PO obviously hadn't done any maintenance to the cooling system.

Flushed the block and radiator. Going to put on the new thermostat with gasket and rtv and bought some radiator flush as well. Going to put it in with some water and run it for a few days including the heater core, to pick up anything that may be left. Will flush it all again this weekend and fill her up with 50/50.

**Also will replace radiator cap and possibly the hoses depending on how well they clean up...

 

So I've been working with it for a month now. Think I am on the 4th flush. Still picking up a little rust. But still over eating.

Now I have this similar problem with my Honda. The electric fan went out so she over heats when I sit for a period of over 15 minutes. On the highway she cools down no problem due to the air flowing through.

The Jeep is experiencing this problem to a T. Exactly like the Honda except, The fan is working fine. I don't understand why it would over heat if the coolant is circulating and the fan is pulling air. Unless the coolant isn't circulating like it should... Could it be the water pump? Possibly, but unlikely, the Thermostat? I'm unsure at this point.

I will add that through several flushes it seemed to have fixed the problem but I never took it on the mountain or anything to test it. After this most recent flush, maybe I didn't get it completely full of water.

Like I said, I'm unsure what is going on. Any help is appreciated! Thanks ! ~ Tom

 

Better make sure she stops over EATING or else she may gain weight and turn into a ZJ! Haha, personaly Id replace the water pump. They only cost like 30 bucks and are fairly easy to swap. Sometimes when the coolant system is really nasty the impeller blades on the pump erode and can't push enough coolant at low RPMs. Just my two Lincolns

 

Haha. Yeah.

Yeah that was one of the suspected culprits. Is there any way to test it before I make any decisions? Is it still possible that there is an air pocket somewhere in the system? I'll check for any leaks tomorrow and see what I find. Thanks for your input!

 

Is 5 weeks later too late?

Time to bite the bullet and replace the rest of the cooling system (water pump and radiator). If the stat came out in 3 pieces, then it was the same thing as constant "wide open" so it was not causing the overheat but rather staying too cool too long.