Willmafingerdo

Hello, i just did a overall tuneup on my 96 jeep 4.0l HO. put a new radiator, fan, waterpump thermostat (195 deg), powersteering pump and belt and other things not assoaicated with the collant system. I filled up my radiator untill fluid came out of my engine temp censor in the thermostat housing put my temp gage back in and filled up the resovour and when i drive it it goes up to 225-230 (would go higher but i stop before it could). I have 1 fan that stays on all the time, and I am driving 25-35 mph. I dont know what else to do, I have been reading tonight so i havent had a chance to try some of the things ive read like feeling the hoses, but i did feel the top hose, it doesnt get warm untill it reached 190 deg i didnt think to feel the bottom hose to see what the temp was on it. I was reading (if i remember it right) that the top hose should get warm first then once the thermostat opens the lower hose will get warm. other than that i dont know what else to try. hot air comes out of my heater so my heater core is working if that would effect the temp at all. hopefully it is just my temp gage is wrong, but i have been driving with the temp gage for almost 1 year and it seems to read the correct temp. If anyone could sugest something to try it would be appriciated.

Thanks in advance.
Will

radio flyer

Did you put thermostat in properly? Can and does happen

Willmafingerdo

yes that is how i put it in

radio flyer

The 4.0L engine is equipped with a reverse rotation (counterclockwise) water pump. The word REVERSE is stamped or imprinted on the cover of the viscous fan drive and on the inner side of t he fan. The letter R is stamped onto the water pump impeller. When replacing water pump, ensure proper pump is installed. Installation of the wrong water pump will cause engine overheating

Willmafingerdo

what is the viscous fan drive? and the letter "R" is on the inside on the impeller? will i be able to see either of these after it has been installed? this is how i put on my fan belt

radio flyer

Look at the history of the 4.0. It was born as a 4.2 - same block, same pump casting, same everything. The 4.2 had a Vee belt.

When they went to 4.0 no change - still the same pump.

When they went to a Serp belt, the way it's strung made the pump turn the opposite direction. No other changes, except now the impeller turned the other way, so the vanes had to be reversed so the water would flow the right way (goes in the top of the radiator and out the bottom.)
On those the OEM pumps had a stamp or embossment - either a R or REV was cast into to housing in the front to identify that it turns the other way. Also the impellers had an "R" stamped on it.

After a few years the serp belt type became the standard, they stopped putting the R or REV on new ones.
When you get a rebuilt most of them are of the older castings - REV or R can be on them. But rebuilders don't always go by that mark.

That leads to massive confusion - the only way to be sure you get the right one is to compare it with the one you took off. Don't go by the REV or R - it may be wrong.
Look closely at the impeller vanes - they should point the same way as your old one you took off. COMPARE THEM!
The castings are totally identical, just the impeller is different.

How do you tell once you put it on? If it overheats fast, and the radiator is not plugged, suspect the pump. Remove the thermostat and put the housing back on. Disconnect the upper hose from the top of the radiator.
Make sure it's full of water.

Start the engine - water should stream out of the top hose like a firehose - if it's correct.
If it's the wrong one, at best it may dribble a bit out of the hose itself, but the water will flow out of the radiator snout - backwards from what it should be.
That test is only valid if the thermostat is removed.

Don't assume the parts house will give you the right one - it may cost you an engine.
Just LOOK!

Reverse rotation pumps [old and new]

Willmafingerdo

if i didnt buy a rebuild pump could it still be the wrong one? when i started it yesterday and was feeling the hoses the top hose was "full" when i would squeeze it it would not colaps(wasnt rock hard or anything, but it wasnt empty). Ill check into the pump here this weekend. Thanks for all the info.

Willmafingerdo

sorry if this is a dumb question, but how does the radiator overflow tank work? will it be full untill the engine gets to operational temp then drains back into the radiator? If the resevour does not empty once the engine is at op temp does that mean something isnt working, and what would that be.. i havent got a chance to mess with it yet just was going to check that also today when i start it up.

freegdr

the over flo tank is for expan sion and contraction when the jeep is at operating temp the bottle should be at the full or hot mark

freegdr

did you allow thermostat to open? then top off when running and in stall rad cap? when this temp is reached are you sitting still or driving?

freegdr

your sure this is how your belt is routed

freegdr

are you sure the belt is tight enough? what about new rad cap

Willmafingerdo

So ill take off rad cap and start jeep, once it gets to op. temp fill it untill full, put cap on and top off resivor to full mark. Yes that is how my belt is run, and it has proper tension on it. The weird thing is i let it idle to operating temp and then let it set for 5 minutes and watched the temp gage and it stayed 190-200 range so i thought it was good as soon as i drive it then the temp goes up. I live in a little town so there is not crazy traffic or anything but just going through town stopping at the stop lights ect my temp would go up to around 230, when i would get in a strech were i could drive it would drop down to around 210-220 then i would hit light and it would go back up. Im sure if i was out of town it would maintain a safe op temp range but i would like to have it able to drive in and out of town I am going to get a rad cap today also as suggested, and from reading over heating posts this seems like a common suggestion. how would the cap cause it to overheat? no fluid is leaking from the cap so it is sealing. I am not arguing that it couldnt be the cap i just wondering how it could effect the temp of the engine. Thanks again for all of the input!!

freegdr

when it reaceh 230 does the aux fan come on?

freegdr

when thermostat opens fill up the radiator bring the idle up higher to make the water go down and put the cap on then let the idle drop down and fill bottle