C

CRS

Well-Known Member

• Sep 13, 2020

• #1

Once the engine on my 3.5 v8 gets up to temperature the rad bung starts leaking, I have replaced this with a new One and seal and the radiator cap that is on the expansion tank but it’s still leaking, it has not overheated as of yet but it’s as if the pressure has no where to go so forces it’s self out the bung. The engine seems to be running fine and the oil is fine. Any ideas.
Thanks

 

kermit_rr

Very

Full Member

• Sep 13, 2020

• #2

Do you mean the drain plug?
Are you getting high pressure in the hoses, are they rock hard?
Has this been happening for a while or just started?
Suggest getting up to temp so the thermostat opens, with the expansion cap off. Does it leak with no pressure?
If it's plastic, check for cracks and smooth mating surfaces for the seal, plastic goes brittle with age and enough heat cycles

 

T

tomcat59alan

Well-Known Member

• Sep 13, 2020

• #3

kermit_rr said:

Do you mean the drain plug?
Are you getting high pressure in the hoses, are they rock hard?
Has this been happening for a while or just started?
Suggest getting up to temp so the thermostat opens, with the expansion cap off. Does it leak with no pressure?
If it's plastic, check for cracks and smooth mating surfaces for the seal, plastic goes brittle with age and enough heat cycles

Click to expand...

+1 isn't there an O ring on the plug that may be hard / cracked as well.if no excess pressure then a bit of PTFE tape may help.

 

C

CRS

Well-Known Member

• Sep 13, 2020

• #4

It’s the plug on top of the rad it screws into it, I have replaced it with a new seal, not tried a bit of PTFE on the thread though. It does not leak if I remove the cap on the expansion tank.

 

cappers

Well-Known Member

• Sep 13, 2020

• #5

Same engine as you. Had a plastic bung and replaced it with a brass one and O ring. Under pressure these was a tiny leak so I just tightened it more and now ok.

 

C

CRS

Well-Known Member

• Sep 13, 2020

• #6

I’ll try tightening a bit more

 

kermit_rr

Very

Full Member

• Sep 13, 2020

• #7

CRS said:

I’ll try tightening a bit more

Click to expand...

With some PTFE

 

norseman

Well-Known Member

• Sep 13, 2020

• #8

capo said:

Same engine as you. Had a plastic bung and replaced it with a brass one and O ring. Under pressure these was a tiny leak so I just tightened it more and now ok.

Click to expand...

+ 1
Brass looks the part as well