SL320 R129 roof strange issue

[Dave320sl]

Hi all . Hoping someone has seen this issue before and has a magic fix for it...

1996 SL320 R129 108k miles.

My roof hydraulic pump is running all the time (until I removed fuse to prevent burnout)
The hard top is in place but it seems to think it is not latched and keeps pulling down at the rear. I checked the manual levers in the boot and they are fully down and latched.

I took off the hardtop manually and the refitted and made sure front and back latched but still the pump is running and pulling down.

I manually raised the soft top, latched it down and the I was able to lower the hood again with the switch all fine ... but the pump carried on and on...


I checked pump has plenty of fluid and I do not see any leaks so i am guessing some electrical micro switch?

I checked many forums and YouTube videos but no one reported same problem I have.

Any advise would be appreciated

 

[grahamcol]

I may be totally wrong here but l have read somewhere about the pump relay on certain models (R170 and the earlier CLK convertible) malfunctioning and causing the pump to over run. Maybe same with yours?

 

[Dave320sl]

Thanks - I did find the statement below on a "rival" forum about a top issue(mbworld.org - I guess we are all friends though)

The motor starting relay frequently fails because it's contacts switch a lot of current (e.g. about 30 amperes). Every time the contacts make and break, arcing causes contact pitting, which over time builds higher resistance to current flow and insufficient power to run the pump motor. Note: In some cases, the contact arching has also caused the contacts to weld together, causing the pump motor run continuously, which will burn or short out the motor if the thermo cut off does not operate properly.

I can take a look at that if I can find the relay ... Any idea where it is on a 96 SL320 ?

 

[grahamcol]

On my R170 SLK it's a black cube like item and from memory it's located near the fluid reservoir for the pump. Sorry no idea where it is on your car but good luck.

 

[Wearsafoxhat]

Possibly inside the boot, behind the trim that hides the battery.
Not sure but perhaps you could pull a relay whilst the pump is running. Quite possibly it will be the hot one !!


Sent from my iPad using Tapatalk

 

[Dave320sl]

Sorry for late reply (6 months) the issue was indeed the relay as it was stuck on. For my 1996 320sl the relay was in the boot below the spare wheel. I just replaced it all and now OK.
I did have to get the relay from the USA and was quite expensive (about 40 pounds) as could not get it in the UK.

Anyway thought I would just conclude on the issue in case it helps anyone else.