by DieselSharker » Wed Mar 10, 2010 6:08 pm
This has been going on about 6 weeks or so. Back in December I replaced the water pump because the weep hole was leaking and threw a new thermostat in there while I was at it. It ran fine for 2 months and then all of a sudden got hot on me one day and has been doing it ever since.
Since then I have replaced the thermostat twice and the fan clutch but still no dice. The last thermostat I put in I drilled a bigger weep hole (1/8") to see what it would do. I've also flushed it several times, including running a bottle of Peak radiator cleaner through it. It runs fine down the highway but in town, especially when I'm just getting off the highway, from a 15 minute or more highway drive, it starts heating up and will peg out if I don't keep the RPMs up. The last couple times I flushed the radiator I noticed small black chunks coming out of it but I run the water through til it comes out clean. You can see the corrosion on the internal fins when you look in the cap. There is no oil in the coolant and no coolant in the oil so I think I'm safe from the head gasket as long as I keep the temps down (knock on wood). I also took the water pump back out to inspect it and everything looked good.
Today I took the thermostat out altogether to see how it runs and it is keeping steady temps below the normal line whether on the highway or in town, so I think it is a flow problem. My theory is the chunks are coming from build-up inside the radiator and causing the flow to slow down too much when the water pump is turning slower. I've flushed it backward and forward through the plug in the head out through the radiator cap and vice versa and also pulled the bottom hose and flushed the radiator top to bottom. I was going to get it rodded but I think having a 20 yr-old radiator rodded might cause leaks.
Any other theories? Should I try getting this thing rodded or drop an extra $130 and get a new one from Napa? I can't afford to get it rodded, have it start leaking, and then have to buy a new once since I'm newly unemployed. I don't think it sounds like a head gasket issue, but I've never blown one before. Thanks in advance.
1991 W250 727, 6" Skyjacker, 37" Dick Cepeks, Gear Vendor O/D, SDX 5x.014s, BHAF, home-made 4" intake, VE tuning & DennyT II pin, GDS 60mm with 16 cm, CoolerTubz 3" crossover
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