I have a 1984 300SD and the coolant pump housing seal is driving me mad. I have replaced it 3 times with and without permatex and it still leaks.

I noticed a small hole below the housing but I never removed a bolt. Not sure why it is there and I don't think this is where my leak is.

Help!

That hole is probably the weep hole for the water pump.
Make sure the housing and engine are very clean, you shouldn't need any sealant, but you can use some to hold the gasket in place.

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83 SD

84 CD

I thought the weep hole was on the actual water pump neck. I can try to clean it better. Both parts were clean and dry except for the tiny bit of residual coolant from the block that just keeps seeping.

Is the waterpump new or old? If the coolant is coming from the weep hole, then a seal is worn out and the w/p must be replaced

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

water pump is old but the coolant isn't coming out of the weep hole. It is coming out of the from behind the housing.

Mine did the same thing. It actually was coming out of the weephole, but did not appear so. I used very thin film of silver RTV as gasket sealer when I replaced the w/p. That was 3 years ago.

Replace the w/p and t-stat and the 41 mm hose that connects the t-stat housing to the block.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Silly me. I was looking at the weep hole on the top and didn't consider there being one on the bottom also. Like you are supposed to see that one.

rrgrassi - Thanks. That was the ticket.

Good thing!
Glad to help!

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K