Ok guys. Ive got an 89 cherokee. I just flushed heavily. Bought it and it had straight water in it. My radiator has a small crack in it as the water froze. Yay... Not enough to cause temperature issues like this due to a slow drip.

Replaced water pump, tstat, all vaccum lines. Cleaned IAC. But couldnt clean throttle body as the stupid torx bolts were stripping when i tried to remove the big unflexible hose that goes to the air box. My idle seems alot better now. Before it was dipping high or low every 20-30 seconds and nearly stalling out. And to top it off new v belt.

Now ive put in about 2 gallons of straight anti freeze. I immagine there was still some water in there. The temp after about 5-10 minuites went up nearly into the red line. Never quite hit the red line. When driving it went higher. Went stopped it dropped down a little bit.

I believe i saw a coolant temperature sensor on the radiator. Is this correct? Is there a way to test if that sensor is working correctly? And the temperature sending unit is near the rear of the valve cover on the drivers side isnt it? Also is there a way to test if this is working properly?

Im just at a loss because ive got no clogs. Heat worked ok but not great even when the temperature gauge said i was almost overheating. Which was rather weird to me.

 

Sensor on radiator is for aux cooling fan only. Sounds like theres still air in the system which will cause high temps or thermostats sticking. Also a weak link in the closed systems the cap on pressure bottle there a Volvo cap that cures the cap issue a search on google should get ya the caps part number also coolant level in bottle will be about half full to allow for expansion.

 

I've heard having too much coolant in there causes more friction and heat, it needs the water too. The whole system takes about 8 liters of coolandt and water, so you have about 7 liters in it now, of coolant, go buy 4 quarts of antifreeze, 90-100%, and top up the rest with distilled water. Maybe someone with more experience can comment too. Just throwing the idea out there, research it a bit. You could work out the percentages of draining some out now and then topping up to make sure its 50/50. And watch out. Coolant is poisonous. Wear gloves and don't just dump it. Take it to a garage or somewhere, where they dispose of it properly. Let me know if you think this could solve your problem.

 

I suppose it could also maybe be your viscous fan thats not working as it should. Or your thermostat is maybe broken. It might not be opening up. You can test it by putting it in hot water for a min or two. To see if it opens.

 

Deff another possibility ...

 

This cap from Napa: 703-1396. Do this first.

 

Any pressure leak will cause temperature issues, as the system depends on developed internal pressure to raise the boiling point of the coolant to maintain it as a liquid, and avoid "steam voiding." Yes, even a slow drip. Or a break in the seal with no drip.

I don't recall what the screws for the air tube are threaded - I'm thinking they're M5-0.8, but I wouldn't swear to it.

For your idle, does it settle down with the engine hot? If so, check to make sure the intake manifold is sealed against the head (inline sixes often have the rear screws work loose on the manifold, especially on side-draught heads,) also check the base of the throttle body and the base of the EGR valve. Else, go over all of the vacuum lines (I know, you just replaced them...) paying particular attention to where the line for the MAP sensor connects to the throttle body - a little RTV black there (be careful!) often doesn't go amiss.

PEDANTISM - It's not a "v-belt" - that's the old-style belt. You have what may be called a "poly-V belt," a "serpentine belt," or a "flat belt."

Did you make sure to purge the air from your cooling system after you'd filled it? A search for that will prove useful (if you did not, you probably have an air pocket behind the thermostat, which will prevent it from opening.)

Antifreeze is supposed to be cut with water for a reason - it will depress the freezing point of the coolant mix, and it has lubricants and useful additives for the pump and cooling system parts, but the boiling point of straight antifreeze is lower than that for water! This is why you need pressure over the water - every 1psig of pressure increase means a 3*F increase in the boiling point of the fluid. If you've drained the system by pulling the lower hose, you may have a half-gallon of water left in the system, which isn't enough for a decent mix. If you pulled the block drain plug (you'll need an 8m/m or 5/16" square wrench, which may be fabbed from a cheap 8m/m or 5/16" hex key, using a grinder, in a few minutes...) you'll have very little indeed.

Also note that, if the system was full with straight water when you got it, it was likely tap water. This is a bad thing - use an indepth flush to redo the sytsem, I like the Prestone two-part flush powder (oxalic acid flush and alkali neutraliser. Follow the instructions, add a step to flush with straight water, then drain thoroughly and refill using a proper cut. Purge the air before returning the vehicle to service.)

RENIX has three coolant temperature sensors - the one in the radiator is the switch for the aux fan (in parallel with the ECU output from seeing the AC REQ signal - if you turn the aircon on, the E-fan turns on.) The one down on the side of the engine, behind the exhaust collector, is the sensor that reports to the ECU. The one at the rear of the cylinder head (driver's side) is the one that drives the gage or lamp on the dash.

If you didn't get any heat from the dash plenum while you were almost overheating, suspect the heater control valve. It's plumbed into the coolant lines, near the "football" tank by the firewall, close to the engine. If it doesn't open, you won't get heat. This may be deleted, if you like - I got rid of mine when I put in all copper heater plumbing.

The football tank itself should be replaced every few years (I change mine about every six, tank and cap,) you can source a replacement assembly from Morris 4x4 Center for a reasonable price.

Also, note that the fan clutch has a service life of 5-6 years, based on my experience. When you replace it, use a Sharpie pen to write the date on one of the tabs where you can check it, this is a common practice with many of the "maintenance parts" I replace (I write the date on the football tank as well. Spark plug, oil change, filter mileage gets written on the valve cover - erase with a wire wheel when you change them.)

Also, what's the mileage on your rig? The OEM RENIX radiators seem to be good for only about 150-180Kmiles before they start to clog tubes, even with good maintenance (this per Jeep wrenches.) The fix? Even the Jeep dealer techs go with an aftermarket unit - get something quality (Modine is good, as is Performance Radiator or CSF. Don't cheap out - there's enough thermal stress on the system as it is.)

 

Is that a better cap for the bottle ? stock one's only last me a little while then blow out . JeepJeep

 

Absolutely. Works well on old bottles, chinese bottles etc, where the stock replacement cap doesn't.

 

SWEET,Thankz gota get me one .JeepJeep

 

If you're gonna keep the closed system, as I have on both my Jeeps, it's a "must have".

 

Yes i am, Thankz again

 

I just went and bought the Volvo cap, put it on and it's now boiling all my coolant out.

Edit: checked the cap, no gasket so I just returned it for another. All good it seems now.

 

Good to hear. You startled me!!

 

Thanks guys. Im not gonna worry about it right now. It seems either the rear main seal or the oil pan gasket is leaking. I lost about 2 quarts of oil on the ground after just filling it. So im gonna replace both of those. need to either seal or replace the radiator. Whichever i can afford first. Gonna try and trace down the fan issue. I know the belt powered fan is working the clutch is fine. Brand new t-stat and water pump so those arent issues. So its likely air bubble or pressure problems but the oil leak is a more severe and immediate issue.