Nevada City Sparky
Jeeper
- Location
- Nevada City, CA
Greetings from the Tahoe Tub Turtles. Sorry yet again for another overheating (and potentially overheated) post.
A friend and I are restoring a couple of '90 Renix XJs with the closed system. We just dropped in a brand new rebuilt 4.0L engine into Turtle #1. We know the engine is dialed since we took 8 weeks scrubing, testing, and working with an extremely reputable local machine shop that delivered us an exellent long block (Reibe's Auto Supply, Grass Valley, CA - no relation, just happy). Long story short, we've researched and done all we can to ensure reliability to this point. Engine started with first touch of the ignition and purred. Pulled valve cover to ensure proper oiling, etc.
Here's the cooling part:
After a first run of about 4-5 miles on that overheated the engine, due to bad burping and a couple of leaks (test #1), we researched this board to make sure we did things right before attempt #2. Here's things we've done and checked since test #1, followed by results of test #2:
Tight turtle? Check, along with hoses.
Open thermostat? Kinda, seems to be flowing, next attempt will be without. Warm to touch when running, but not too hot to hold onto. Not sure on bleed holes, believe there was one on it, but not sure. We'll check.
Water Pump? Water pump was from old engine (one of the few areas we skimped). Appeared to be solid, and rumored to be replaced 6 mo. prior to our rebuilding adventure (we're doing a pair of engines at once).
Fan? Used, but again clutch appeared to be working.
Raditator? Potential suspect. Could be ancient. More on this later.
Burping procedure? OK, we took this part (cooling system) of the project a bit more seriously now ;-) , we'd been warned the night before by an angry turtle under the hood 8-o , so we made sure to fill up first the radiator through the top raditor hose till it came out the water pump. Filled reservoir till it stopped gurgling. Popped temp. sensor and watched coolant squirt out.
Results of Test#2: Engine started fine and idled comfortably. Massaged radiator hose a few times and opened and closed turtle several times. It was friggin' cold last night, so we waited to ensure the upper radiator hose was nice and warm, but we got out of there before it could get too hot to touch after freezing our butts off in a gas station parking lot. Noticed that fluid, which ran strong, "surged" as it entered the turtle. Idled to 215° on the dash gauge. We drove it home and it stayed at that temperature as long as we were on the freeway (about 4-5 miles). When we got off the freewya and got down to 25 mph, the temperature started to rise. Took only a few minutes to get into the red and start squirting from the valve on the turtle.
So, what causes overheating at low speed? I suspect flow, which means thermostat, pump, or radiator.
One other thing that might contribute: when we put the radiator in, we added an oversize (approx. 14" x 8") trans. cooler in place of the old original stock trans cooler that was there. Could it be blocking air flow enough to make this big of a difference?
A friend and I are restoring a couple of '90 Renix XJs with the closed system. We just dropped in a brand new rebuilt 4.0L engine into Turtle #1. We know the engine is dialed since we took 8 weeks scrubing, testing, and working with an extremely reputable local machine shop that delivered us an exellent long block (Reibe's Auto Supply, Grass Valley, CA - no relation, just happy). Long story short, we've researched and done all we can to ensure reliability to this point. Engine started with first touch of the ignition and purred. Pulled valve cover to ensure proper oiling, etc.
Here's the cooling part:
After a first run of about 4-5 miles on that overheated the engine, due to bad burping and a couple of leaks (test #1), we researched this board to make sure we did things right before attempt #2. Here's things we've done and checked since test #1, followed by results of test #2:
Tight turtle? Check, along with hoses.
Open thermostat? Kinda, seems to be flowing, next attempt will be without. Warm to touch when running, but not too hot to hold onto. Not sure on bleed holes, believe there was one on it, but not sure. We'll check.
Water Pump? Water pump was from old engine (one of the few areas we skimped). Appeared to be solid, and rumored to be replaced 6 mo. prior to our rebuilding adventure (we're doing a pair of engines at once).
Fan? Used, but again clutch appeared to be working.
Raditator? Potential suspect. Could be ancient. More on this later.
Burping procedure? OK, we took this part (cooling system) of the project a bit more seriously now ;-) , we'd been warned the night before by an angry turtle under the hood 8-o , so we made sure to fill up first the radiator through the top raditor hose till it came out the water pump. Filled reservoir till it stopped gurgling. Popped temp. sensor and watched coolant squirt out.
Results of Test#2: Engine started fine and idled comfortably. Massaged radiator hose a few times and opened and closed turtle several times. It was friggin' cold last night, so we waited to ensure the upper radiator hose was nice and warm, but we got out of there before it could get too hot to touch after freezing our butts off in a gas station parking lot. Noticed that fluid, which ran strong, "surged" as it entered the turtle. Idled to 215° on the dash gauge. We drove it home and it stayed at that temperature as long as we were on the freeway (about 4-5 miles). When we got off the freewya and got down to 25 mph, the temperature started to rise. Took only a few minutes to get into the red and start squirting from the valve on the turtle.
So, what causes overheating at low speed? I suspect flow, which means thermostat, pump, or radiator.
One other thing that might contribute: when we put the radiator in, we added an oversize (approx. 14" x 8") trans. cooler in place of the old original stock trans cooler that was there. Could it be blocking air flow enough to make this big of a difference?
