hey there,

81 240D

was overhauling my cooling system b/c it creeps up to 100C when driving 75. replaced all the hoses, took the radiator out to have it flushed and cleaned, and replaced the water pump (although it probably didnt need it, but i bought a new one so in it went). When i pulled out the two right-most bolts that hold the water-pump housing to the block, they were covered in black oil! Is this normal? Do those bolts screw into a part of the block that oil circulates through? or is that indicative of a blown head-gasket??? I have been trying to hunt down this heating problem for a while now and it still gets hot on the highway! Currently, i have the thermostat out just to narrow down the problem (i tested it in boiling water and it opens when it should) The car runs fine otherwise and i dont have oil in the coolant or coolant in the oil. should i suspect a beginning head gasket problem?

thanks for any help.

Hello jpmaynard
Suggest:
#1. Replace coolant temp sensor.
#2. Install aftermarket temp sensor and gauge to verify temperature.
#3. Check your cooling fan clutch.
#4. Test the electric cooling fan for function.
#5. Have a compression test done.
#6. Have a leak down test done.
#7. Don't let them fool you, #5. and #6. test for different things.

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Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
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1985 300SD
1983 300D
1984 190D
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I will probably replace the sensor first. I think i read about testing it by pulling it out and heating it in water with a thermometer.

The fan is a solid mount so i dont have to worry about that.

but does anybody know if alot of oil on the water pump bolts is normal?

oh and the electric aux fan is wired to the AC which doesnt work. I am planning on wiring it with a relay switch to help out on steep climbs, but i dont think that will help me out when im going 75 on the highway. also seems more like a band-aid then a cure.

For the orig question, YES, they screw into the timing chain area, just make sure you use thread sealer (ultra-black RTV or something like that) on the cleaned threads before re-installing them.

For the auxilliary fan, I've worked on a LOT of A/C systems since summer started here and most of the problems with the fans are one of two things;

1. Fan bearing decomposed causing the motor to lock to the magnets (none or rough movement.) Replace bearing with a SEALED bearing #NTN 6001 (straight forward replacement).

2. A/C fan temp switch bad. The switch at the receiver/drier with the pigtails coming off. D/C the fan wires and short together with a jumper. If the fan comes on, then the temp switch was bad. Check your local import parts houses for one. Dealer wants $46, best online source wants $25, I buy them at the local imports place for $17.

Another problem with the fan if it does not run when jumpered is the bushings can melt through the plastic guides and cock sideways, but I've only seen that on one fan out of a dozen or so.

For the stock thermal clutch, do the Toyota viscous fluid mod, did the trick for a few overheating cars I've had here. I now buy the 10k cst fluid from Toyota in quantity.

__________________
1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


=========================

"If you don't know where you are going, any road will get you there". Lewis Carrol

I just want to clarify that I dont have a clutch type fan, its a solid mount right to the water pump pulley.

The aux. fan in front of the AC radiator is something that I plan on hardwiring to a switch.

I remember at one point I put a thermometer in at the top of the radiator and watched as the temp climbed and compared what I read on the thermometer to what was on the gauge in the car. If I recall, they were pretty similar at that point. I think i may take out the sensor and heat it in a water bath w/a thermometer tonight to compare directly.

Thanks for the help guys!

Joel

Hello jpmaynard
Suggest:
#1. Have a compression test done.
#2. Have a leak down test done.
#3. Don't let them fool you, #1. and #2. test for different things, you need both.