[jforb]

Hi, I'm going to tackle the cooling system on my car. First up is the leaking heater hose, heater side of the control valve, under the cover at the top of the firewall. The hose was pretty bad at one end. I managed to get the cowl vent covers off, and removed the other end of the hose from the heater core.

Can you replace this with a straight hose, instead of buying a molded hose from MB? It looks like it might...perhaps I'll give it a try.

.

Same for the hose from the coolant tank down to the bottom of the radiator?

Looks like the heater hoses at the back of the engine are "fun" to get to, also.

Then...the heater control vacuum valve, of course mine is broken, and I can't tell yet if it leaks because the hose connected to it was leaking. Should I go ahead and put a manual valve here? or one that's operated by a pull cable? I don't expect I'll get the vacuum system working any time soon, it's a complete mess. Everything is disconnected, and finding where they all go is challenging, because most references are to another model of SL, than what I have.

 

[GearheadGreg]

I have an '83, so I'm not sure if I'm talking apples to apples here, but when I did mine, I had to remove the lower windshield trim to allow the removal of the cowel vents. In there, I then had to depress the vent flaps to gain access to the ends of hoses and clamps. And no way would a hose work that wasn't a correctly molded hose. I urge you to get the MB hoses. Also, filling the coolant system under vacuum was necessary, for me.

 

[jforb]

Hmm....I went to the parts store and got some 3/4 hose (I ran out last summer when I overhauled the engine for my old truck)....and was able to make it work for the short run from heater core to control valve, and also for the long run from coolant tank to lower radiator. I filled it up with water and went for a test drive, the system is holding pressure now. I guess that means I'll be able to find the next weak point!

I'm hoping to take a trip where it's cold at the end of spring, so I need to figure out the heater control valve still. It would be nice to have heat when I want it. AC I don't need so much.

 

[RaceDiagnostics]

You just need to keep an eye on the heater hose to ensure it doesn't kink. The one down from the coolant tank will be fine I'm sure as there is no tight bend.

As for the heater valve, I got rid of mine and changed it for an electrically operated one from Summit racing/vintage air.

 

[jforb]

thanks. Looks like I got lucky, the only hoses that really needed to be replaced don't have sharp enough bends to need molded ones. The other heater hoses all look to be in good condition.

I'll have to do some investigating into the control system for the heater...

and also need to seal up the two cowl vents at either side of the top of the firewall. The seals are mostly missing, the remains are hard as a rock. I did put some new foam around the cover plate in the center of the top of the cowl before replacing it.

 

[Shepherdcl]

I have a 350SL that left the factory in May 71. Looked just like yours. 5 years ago I was doing what I call "MAJOR" rust repair. While the body was mostly bare metal we decided to take out the heater core, air box, vacuum valves, etc. and replace with a vintage air system. It works great, and has AC. Point is I kept all the original stuff, so if you sort out the vacuum controls and end up needing a part let me know. I'll unbox and see what's still working!

 

[RaceDiagnostics]

I have a 350SL that left the factory in May 71. Looked just like yours. 5 years ago I was doing what I call "MAJOR" rust repair. While the body was mostly bare metal we decided to take out the heater core, air box, vacuum valves, etc. and replace with a vintage air system. It works great, and has AC. Point is I kept all the original stuff, so if you sort out the vacuum controls and end up needing a part let me know. I'll unbox and see what's still working!

Do you have some details on your vintage air system, would be very interesting.