arbitris

I'm having constant issues with temp on my Jeep and I'm hoping somebody might be able to help me find a solution, or even a starting point. I've done a lot of troubleshooting and reading, and I'm kind of sitting in the corner shaking my head at this point.

I have a crate engine that seems to want to run hot no matter what I do, no thermostat, low temp thermostat, drilled thermostat, highway driving, around town cruising, and sitting in the parking lot, all have the same effect. The longer it runs the warmer it gets, the more you push the loud pedal the warmer it gets, I always shut it off about 190-200degrees (yes not overheating yet, but I shut it off to prevent overheating) After shutting it off, the temp slowly rises up to 30 degrees. If I wait a minute and run the engine for a minute it drops back down to a few degrees under what I shut it off at.

The exception: Last winter when I had no thermostat in it for a short time during the snow storms. I didn't go far, but 5 mile drive would bring it up to about 140-160 degrees.

GM Crate 350CI 250hp pre-1986 engine with low mileage
unknown performance cam,
Edelbrock carb,
Edelbrock aluminum intake manifold
edelbrock water pump, (v-belt clockwise rotation)
3 core down flow radiator size: 17"x21" (excluding tanks)
Visual inspection of the inside of the radiator through the cap looks fine,
solid bolted flex fan (checked for correct rotation)
-and- 1500cfm electric pusher fan set to run 100% on the front of the radiator.
Fresh tuneup including:
fluids, filters, wires, plugs, distributor cap, rotor, weights, HEI module
Timing: I attempted to time it with a light, but my timing mark is about 1/4 turn off of the timing chain guide plate. I timed it by ear, and retarded it a little (A practice I was taught as a kid and have always used)

Possibly related issue: Sometimes (often) when trying to start it, the starter will turn for 1/4 second and then just spin freely, I'm figuring either I need a new starter or I had too much timing in it causing it to "kick back" from a compression cycle.

The engine is sitting in a:
1986 Jeep cherokee 4x4 4 door
TH350 trans
MASSIVELY louvered hood, air flow is definately not the problem.

Again, thanks for any information or direction.

SWHouston

You've certainly done your homework on it...

Crate Engine...Has it been bored, and if so, how much ?

Have you had the headroom in your Radiator "sniffed" for Fuel Fumes ?

Done a Mechanical Temp check to see if your sender/gauge is really telling you the right temp ?

Have you ever pulled the heads, and seen that it had the right set of Heads and Gaskets on it ?

You still might pull the Hood off and see if the additional flow would help any.

MDTAHOE

What is the highest temp it goes too?

SWHouston

I just re-read your post, and saw your note on the Edelbrock pump.

Is that supposed to be a High Capacity Pump ?
Is it possible that it's moving the Coolant through so fast, that is isn't having time to cool down ?

arbitris

I don't smell any fuel in the tank.

The engine is a GM crate engine manufactured a couple years ago as a replacement, not a reman.

Top temp I have ever let it get to before shutting it off is a little over 230.

another test I did yesterday was to drive it a few miles until it got quite warm, it did start to idle rough and try to stall and lose power. I then parked it at home and ran a garden hose over the radiator for a minute and check. No temp change, rev the engine to 2k rpm's for 15-30 seconds and the temp would drop 10 degrees or so, repeat, another 10 degrees, brought it back down to about 180 and shut it off.

I don't know which pump it is aside from matte aluminum finish, edelbrock brand in the casting and a v pulley pump on it, (help on how to identify which pump I have would be nice) but I doubt it's getting too much flow. If anything I would say this sounds like it's not getting nearly enough flow, I'm wondering if the inpeller on the pump is supposed to be reverse direction, or if I have a large pulley that just isn't turning it fast enough I have over an inch of clearance between the pulley and the water pump housing all around.

I also noticed that I don't ever hear the fan flow/strain on the engine like I do on my blazer when the fan clutch engages and you can feel the power loss and hear woosh from the fan pushing.

SWHouston

1) You won't be able to smell Fuel. You need a "sniffer" (chemical analyzer) that's a lot more sensitive than you nose.

2) Not that it's a good idea to let your temp get this far, but with a good Cooling System, you're contained until you get to about 268°. That is, with the 16 Lb Cap, where your boiling point is.
Do you have a Reservoir, or is it just an open Tube ?

3) For curved Impeller Fins, they should be arched in the direction of flow. If you have straight Fins, then you need to see the pump discharge tube (inside the engine block) to actually tell which direction it should turn.

4) You said you have a Flex Fan. They won't sound like a Clutch type.

arbitris

1- Good to know, and I'm guess this is looking for possible blown head gasket?
2- I am using an overflow tank.
3- If a smaller water pump pulley doesn't solve it (when it gets here), I'll open up the pump and check the fins.
4- Good to know, although this will be the next thing to go in favor of the setup that is working in my blazer if the pulley alone doesn't fix it.

SWHouston

1) Blown/seeping, yes. The high temperature gas can really increase the water temp.
2) If you extend the Tube down into and below the Level of Coolant in the tank (when cold), you'll have a Recovery System ! Assuming you have the right Radiator Cap.
3) A smaller Pulley is going to speed up the Pump. Are you sure that's what you want to do ?
4) What's the Blazer setup like ?

therewolf

What's your coolant ratio?

arbitris

The tube is at the bottom of the coolant tank, I'm a huge fan of taking advantage of an easy recovery setup.

I'm assuming that I have the wrong pulley on the water pump and do want to speed up both the pump and fan. Largely because last time it got hot, speeding up the engine helped it cool off.

My blazer is actually a bone stock 2004 4.3L Vortec.
serpentine belt setup (reverse rotation pump), fan clutch, plastic fan, 195 degree thermostat

Coolant ratio: 49%coolant 49%water 2%air bubble after opening the cap.

Oh, one more note, I live at 6500feet elevation and the air is REALLY thin here, a lot of vehicles have cooling issues because the air isn't thick enough to cool the radiators.