cooling again & again & again.......

[Pharaoh XJ]

GUYS I have a cooling issue !!!

my 94 xj 6 cyl has some cooling issues

The temperature rises on the highway & in the city till it reaches 220, I used to stop open the hood turn on the AUx fan & it used to cool down in minutes, now it only goes up the only solution is to turn off the engine.

So I though that it was something to do with the thermostat so I removed it & installed it with no stat, turned on the engine blocked the rad & waited till the 220 mark, then unblocked the rad, turned on the AUX fan.

Nothing happens the needle is stationary for 5 minutes

But when I rev the engine to 3000 rpm a couple of times the needle instantly goes down.

so its not a stat
the water pump was changed 4 years ago & 35k miles ago.


HELP !! the wheeling season is about to begin & I am crippled

 

[Begster]

Hold old is the radiator? Did you flush the system out?

 

[solomon7]

Mechanical fan clutch?
If it's not engaging properly you'd need higher rpms for it to work as it should at lower rpms. If the clutch is dead the blades will only spin at about 30% of the pulley speed. Not enough.
Upgrade to the 97-98 ZJ HD fan clutch. NAPA part#272310 about 43 or 44 bucks and half hour to install. Just pull the electric fan/shroud as a whole, and the stock shroud and fan out as a whole assembly and reverse to install. be sure to stick a piece of poster board over the radiator fins to avoid damaging them and yourself. The back of my hands looked like I ran them through a planer afterwards without it!
ONLY get the HD not the maxkool version, it's too big.
ONLY get NAPA PART #272310 No where else has the right fan.
The clutch engages stronger and cools better than stock. IT also makes a nice whirr!

Flush your cooling system with a 6 hour flush while you're at it. Xerex makes a nice one for about 6 bucks. Stick it in drive for a few days, drain and fill with appropriate mix.

 

[Pharaoh XJ]

-Rad is 2 years old I broke the plastic sleeve so sleeved it with custom copper sleeves
-as for the FAN clutch I am using a locked fan clutch ( i adjusted the coil at the back so its engaged full time )

What else can can cause that could I have a faulty gauge/probe
- water pump ?
- internal engine ( has 160 k miles)
- I have a cracked manifold ??

Suggestions

 

[joe_peters]

Test your way to a solution.

Get your hands on a cooling system tester and check for HC in the coolant.

Stretched timing chain will allow overheating.

Radiator is two years old--how old is the cap? Without proper pressure the coolant will boil about 45 degrees F (25 degrees C) EARLIER than it should.

Running a 30/70--30 ethylene glycol to 70 distilled water mix is better in your region than a 50/50--but you likely know that already.

 

[Pharaoh XJ]

Test your way to a solution.

Get your hands on a cooling system tester and check for HC in the coolant.

Stretched timing chain will allow overheating.

Radiator is two years old--how old is the cap? Without proper pressure the coolant will boil about 45 degrees F (25 degrees C) EARLIER than it should.

Running a 30/70--30 ethylene glycol to 70 distilled water mix is better in your region than a 50/50--but you likely know that already.

Stretched timing chain will allow overheating ?
Does that mean I have a retarded or advanced valves ?

 

[Pharaoh XJ]

is that normal

VIDEO

 

[Pharaoh XJ]

bump !

 

[orange]

--Do NOT open radiator cap. If opened START OVER HERE!--

Watch the coolant recovery tank (CRT) level. Cold (overnite) engine- between ADD and FULL marks. warm up engine 5-10 minutes level should rise say 1/2 - 1 inch. cool back down (hours) level should go back down.
Add coolant to keep level, cold, between ADD/FULL marks on CRT --- ONLY ADD TO THE CRT, DO NOT OPEN RADIATOR CAP.---
The tube from the radiator fill neck to the CRT must not leak AIR .
If CRT level is NOT going up and down, as above, engine will have air in the system - NOT GOOD! Its NOT burping the air out of the system. The tube from the radiator neck to the CRT must be in good condition with NO air leaks.

Air bubbles around the temp sensor can give the sudden changes in readings.

Park with the left front highest to help the the burping. It may take a few hot/cold cycles (overnites) to work the air out.

IF RADIATOR CAP IS OPENED = START OVER. Add topping off coolant ONLY thru CRT.

Good Luck,
Orange