1987 740 spilling coolant from radiator plug

Today I was sitting in a long line at a drive-through restaurant, like

30 minutes in 100F weather with the engine running and A/C going.

The temperature gauge never went above about 1/2 way on the dash, which is the usual range for the car. When I parked the car I noticed antifreeze spilling on the ground.

I opened the hood and the hoses were fine, but on the passenger side near the top of the radiator is a plug with a large metal nut and a plastic plug in the middle. It looks like an access point for the aux fan thermoswitch.

Coolant was dripping from there. When I got home it did it again and so I tightened the nut 1/8-1/4 turn and it stopped.

I took a short drive and it did it again. I am sure it was the long idle that did this. Here is what I checked:

Both intake and outgoing coolant hoses were soft and flacid, I am thinking the thermostat is opening. The overflow tank was fine, only dripped down from max to min.

When I opened the overflow tank, there was pressure and it relieved when I opened the cap.

Is this normal (but needs to be replaced) because it is a plug used to fill a spot where a switch should be? Or should I be concerned?

Thanks, Jamie

Reply to
Jamie
Loading thread data ...

My first thought was what the hell were you thinking sitting in a drive through for 1/2 hour? Park the car and walk into the restaurant....

The radiator cap is supposed to pop open or fail when there is too much pressure in the radiator so I would think that it should be replaced if it's old. I forget the PSI they blow at. So there is too much pressure in the system and the coolant found the easiest way out.

Next time park the car in the lot and walk in...

Jabber 1999 S70.

Jamie wrote:

Reply to
Jabber

Bad experience at the drive in. I was the only car there, waiting like a dumb-ass, 35 minutes at the window of a local restaurant and ended up still not getting my food and had to go inside for a refund.

At any rate, this could have been anywhere, maybe idling in rush hour traffic - who knows?

The thing is that the temperature gauge didn't go very high and even this morning after a short drive in cooler temperatures and the engine warmed up - this plug was dripping.

I think that someone disconnected the Aux Fan, because the thermo-switch is loose beside this plug. They put some plastic plug inside the hole and I am wondering if it had no sealant, or if the sealant failed.

This weekend I am going to pull the plug and reseal it with heat resistant sealant.

I was mainly curious to know if this is common for these plugged holes to leak.

Thanks!

Jabber wrote:

Reply to
Jamie

I was thinking in terms of heat and not pressure, Jabber. I'll replace the cap also, in case it is not releasing pressure. I should have realized that when the overflow tank was pressurized.

JB

Jabber wrote:

Reply to
Jamie

The same hole was filled with a "freeze plug" in mine, and the pplug came out about a week after I go the radiator. I epoxied a plug in it and have been happy since. As long as yours tightened down I think you have it fixed.

Mike

Reply to
Michael Pardee

Still leaking through the plug hole, not the threads. I'll do epoxy and maybe replace the cap.

Thanks.

Michael Pardee wrote:

Reply to
Jamie

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.