Coolant Leak in the OBC Plug area.

[BMWLOCO]

Fellow Enthusiasts:

Refreshed the whole cooling system, timing belt, pump, etc.. No coolant leaks, but I notice some coolant on top of the OBC plug and on the garage floor after I test drove it yesterday.

Could it be that I put too much coolant in the system?

Yesterday, I took a shop cloth and cleaned the top of this part and sucked up all the coolant from there. I didn't drive the car at all, and this evening, I notice more build-up of coolant in that area.


It's where parts 23-27 go. I looked up on the hoses that are on top of that area and they are all dry. The coolant hoses from the bottom side of the throttle body are all fitted and good.

What is the purpose of this plug area?

Thanks in advance!

[scottinAZ]

check to make sure the freeze plugs arent seeping in that area.

[BMWLOCO]

I think that the freeze plug is leaking exactly where pictured below:

[scottinAZ]

wouldnt surprise me one bit to find the plugs just above the plug there are rotten. only takes a small pinhole to make a huge damn mess..... been there, done that, got the t-shirt. good thing is they are fairly easy to change out.

[delatlanta1281]

Can you not see it dripping down when the motor has warmed up? Did you replace the thermostat?

[BMWLOCO]

Can you not see it dripping down when the motor has warmed up? Did you replace the thermostat?

I did replace the thermostat with the Cooling System replacement kit from Pelican.

I don't see any dripping, but I'll recheck. I suspect that that plug is loose somehow. Unless something is falling exactly on it. I felt for coolant on the thermostat hoses and nothing. I cleaned the plug and didn't even drive the car and there's more coolant there.

I'll keep looking...

Keep them coming..

[jlevie]

Pressure test the cooling system and I'll bet that you will find the leak. It may be from a freeze-out plug, the head gasket, or the thermostat hosing/hose.

[BMWLOCO]

UPDATE:

Looks like the coolant is coming from the hoses under the Thermostat housing. The small (t-stat to throttle housing) and the larger one (heater hose) have coolant dripping from them and it's coming down to the floor and the OBC area.

Would just cutting the hoses a bit and re-clamping help? or do I need new hoses?

I also have some seeping coming from the water housing on the throttle body, so the gasket is getting replaced.

I think that's about it..

Thanks again..

[Rigmaster]

UPDATE:

Looks like the coolant is coming from the hoses under the Thermostat housing. The small (t-stat to throttle housing) and the larger one (heater hose) have coolant dripping from them and it's coming down to the floor and the OBC area.

Would just cutting the hoses a bit and re-clamping help? or do I need new hoses?

I also have some seeping coming from the water housing on the throttle body, so the gasket is getting replaced.

I think that's about it..

Thanks again..

You can try trimming them and reclamping, but if the hose is soft or has a hole in it, you'll need new ones.


The water housing gasket on the TB is a common sneaky leaker, you can bypass it (just connect the 2 hoses together) if you want, and just replace the gasket when you get time. Some people have it permanently bypassed with no problem.

[BMWLOCO]

You can try trimming them and reclamping, but if the hose is soft or has a hole in it, you'll need new ones.


The water housing gasket on the TB is a common sneaky leaker, you can bypass it (just connect the 2 hoses together) if you want, and just replace the gasket when you get time. Some people have it permanently bypassed with no problem.

Could you please expand on the bypass procedure? What do I do with the extra hose that carries the coolant?

Thanks..

[dude8383]

Can I just ask what you mean by the "OBC area"?

[BMWLOCO]

Can I just ask what you mean by the "OBC area"?

It's actually called the "OBS" Plug, or "bearing cover" according to Pelican and Tischer's sites.

Take a look at my pictures above and the Diagram of the engine.

R..

[Rigmaster]

Could you please expand on the bypass procedure? What do I do with the extra hose that carries the coolant?

Thanks..

just take both hoses loose from their fittings on the TB housing and connect them together. You'll need to find a small piece of hard tubing or a barbed hose fitting to join them, then clamp both sides and you're good!


All you're doing is taking the TB housing out of the loop. Honestly, you could probably get by with just plugging both of the lines once you take them off the TB, but I usually just connect them together as above.

[JrCamacho]

just take both hoses loose from their fittings on the TB housing and connect them together. You'll need to find a small piece of hard tubing or a barbed hose fitting to join them, then clamp both sides and you're good!


All you're doing is taking the TB housing out of the loop. Honestly, you could probably get by with just plugging both of the lines once you take them off the TB, but I usually just connect them together as above.

i need to still do this... ;)