Join Date: Apr 2009
Location: Chandler, AZ
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Darn it!! Still running HOT!
Sorry I don't post often, busy at work lately.
So here is the latest:
I took the water pump off to check to see if the impeller was any good, because judging by the outward appearance that thing was old. I got it off and looked at it carefully and noticed that the impeller has been turning the wrong way this entire time. Eureka, I thought! Since I spent the time to get it off, a new one wasn't that expensive, and I couldn't be absolutely sure it wasn't slipping or something I decided to just put a new one on. While I had the water pump off I hooked up the power washer and was thinking I might see a big wad of crud come shooting out when I sprayed out the top and bottom holes where coolant travels. But no... clean. Then I cleaned the contact areas thoroughly and lined it with some coolant system approved sealer and slapped the new one on there. I had to order a double V belt from a tractor supply store (made by Gates Corporation) so that I could make the water pump turn the right way. I was hopeful that this would fix my overheating problem... but nope, virtually unchanged.
Not that there are millions of Jeeps out there with Buick 350's but this is something you may want to consider about your Jeep (or car for that matter) if you do have a Buick 350. Take the water pump off and manually turn it. If it's like mine the water pump impeller is designed to turn counter-clockwise while the crank turns clockwise (be sure you imagine the way it must turn when actually attached to the engine, not just in your hand). You have to run the BACK of the belt to the water pump in order to accomplish this, and the only non-ghetto way of doing that is by buying a double sided V belt. Size AA fits exactly, but they are sold in only hugely long lengths, so I had to buy size BB and trim off the little ridges on each side with an exacto knife. It fits great. You can bet that before I went through all this bologna that I was good and sure which way it was supposed to turn! Just a little tip I stumbled upon. This may be why I have seen in several posts people really having problems after buying water pumps at auto parts stores for the Buick 350.
While I had it apart I checked the upper and lower radiator hoses. No leaks, like I mentioned, and both have the integrated spring. They are in pretty decent shape, and the lower hose doesn't collapse on revving the engine. Notably, the upper hose doesn't arch really high to let air into the system. But to be sure...
I drove the front tires up on the curb to be sure the radiator was the highest point and added coolant mix until it was full to be sure there was no air anywhere in the system. There are no high arching loops of heater hose to/from the heater core. I was hoping this would allow the system to pressurize better, but it made virtually no change.
By the way, will it do any harm to take out the heater core and just cut the hose really short and bypass it? It basically is just heating up the passenger compartment even more than the overheating engine already does. The heater housing is all broken and rotten and useless, and the knobs to operate it are all stripped and crappy anyway. I'm just wondering though, does the heater core act like a mini radiator?
I built a fan shroud from sheet metal. I cut out areas for the power steering pump, the alternator, and 1 hose, but the rest of the shroud stretches to within about 2 inches of the block on all sides. Virtually no air heads out toward the wheel wells, and you can even feel a strong breeze at the rear of the engine compartment. I thought the shroud might fix the problem. Nope. Even after the sweet Spal dual fans blowing the wicked witch of the west back to Kansas, focused by a nice shroud it still overheats on the freeway, and will even get hotter at idle at stoplights (but if you ONLY drive on back roads, it won't get above about 210).
I thought this may simply be a problem with venting out the hot air. So I cut about a 2" X 12" rectangular hole in the firewall and vented the engine compartment out through the area where the A/C and heater (both long dead and gone) used to vent under that louver looking thingy in front of the windshield. I figured hot air rises and this was the highest part of the engine compartment. Don't worry, I kept the little trough intact with the drain tube that channels rain and snow out into the engine compartment. That way rain and snow can't just run in and onto the engine. I think doing that for the better part of 2 hours helped about... none. No change in the overheating problem.
I went out and bought a laser thermometer (only $30 at AutoZone if yer looking) and checked the radiator. Like you said it seems to be working properly because it showed about 140 to 150 all the way across the top and down to only about 100 near the bottom. No hot spots anywhere. It seems the engine is hot but the coolant is cold, how the hell can that be? It's 100+ degrees out today.
I ran the Jeep down the freeway again a couple of exits until I got borderline hot at 230 and pulled off. I left it running and jumped out and checked the hood temp with the laser, and hit the engine compartment with it too and neither was hot. Nowhere near 230. Then I started checking the exhaust and intake manifold (more on that in a sec) and in the 10 minutes I spent checking temps all over the place the temp cooled down to 180 degrees at idle. I revved it for about a minute just to see what happens, and it jumped up about 20 degrees, even with the hood wide open and the fans blasting. How can you get more ventilated then that? I bought some 3" by 10" fender vents but I'm highly suspicious they won't do a darn thing.
When I used the thermometer to run the exhaust from front to back I thought I found something interesting. Right under the cylinders gets hot at about 400 to 450 degrees but as you travel back down the headers it gets cooler as expected, right? However, on the driver's side just above the heat riser I noticed the temp was about 500, whereas on the passenger side in the same bend where the heat riser would be is about 400 degrees. So, I took the exhaust pipe off the driver's side and looked up in there. No visible blockage, and the heat riser valve is in the open position. With the exhaust back together I started it and walked back to the back and it feels like the same pressure is leaving the pipes on both sides. The exhaust pipes just run straight back with no crossover. Then for giggles I ran the engine until it got hot again at about 230 and looked at the heat riser to see if it moved or did anything weird. It stayed the same. Just to confirm for my own sanity, the heat riser is open when the arm from the thermostat is fully extended toward the front of the vehicle, right? I grabbed the lever that the arm attaches to with plyers and it seems to move fairly well when you give it some good force, and it returns to the same place. Seems like the spring is working. Guess it isn't the heat riser????
I adjusted the carb air/fuel mixture richer until I got it running so rich it stunk up the place and ran like crap, then backed it off just until it ran okay. I drove it and it still got hot. Guess it wasn't running too lean????
The timing has been adjusted with the light and is good. No change in overheating. Guess it isn't the timing????
I checked the expensive ass synthetic oil I put in it and it remains topped off and very clean. That isn't helping much either.
I even hit the heater core with the thermometer and it reads in the 140s. What the?
Any more ideas?
Guess I move on to the vaccuum guage? Can you tell me how to interpret the numbers I get? I don't know really what I'm looking for because I have never used one.
Thanks to all of you who are better at this than me and taking time out to help me. I feel like some super stud mechanic would be able to figure this dang thing out. Know anyone in the East Valley of Phoenix?
I really like working on the Jeep, I just am ready to figure this darn overheating thing out already and move on to other projects!! I just wanna drive my cool ass old beast to work every day. HELP!!!!
Last edited by kirk211; 07-04-2009 at 03:58 AM.
Reason: Forgot something