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M119 thermostat renewal

2K views 6 replies 6 participants last post by  ka707 
#1 · (Edited)
Hi all, my 1993 SL 500 was taking a while to warm up and never really reached the 80 degree mark.Everywhere you read about this job seems to start with removal of the fan. Well I just could not shift the 8mm allen bolt in the middle, tried locking the fan across the 4 bolts with a metal pin while I tried loosening the allen bolt but that just broke. However while I was looking at the job I figured it could be done without fan removal, in fact I didn't even remove the drive belt.
After draining the radiator and removing the elbow hose at the thermostat housing I used a 1/4 inch drive ratchet with a 2 and a half inch extension to remove all 3 bolts, I found it easier NOT to use a universal joint to get at the difficult bolt, and no need to remove the dipstick tube either. Put something over the top of the open water pump outlet to stop things dropping in.
I did renew the elbow hose along with the thermostat(all genuine parts)and found it easier to put the new one on without the jubilee clips in place. I opened the clips fully then put them on after the hose was on.Job done and car now reaches temperature, hope this helps someone who may be nervous of attempting it :smile
 
#5 ·
as mentioned. no need to remove the fan. but of all the work I've done on the E420 and SL500, the toughest job yet was the thermostat on the E420. That M119 thermostat is NOT the easiest thing to R&R !!. tough getting to all the bolts, tough getting the hoses back on.
 
#7 ·
Just replaced mine, at 100k klms, it too was getting lazy, took the car a good 30 mins to get to 80c and if running on the freeway would hold around 60c.

I found that undoing the dipstick made it easier to access. I uses an articulated socket and an extension, was not too bad. I also found removing the hose completely made the replacement job a whole lot easier to align. Care on the bolts, easy to cross thread!
 

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