I'm in the process of tweaking a 6 cyl Mercedes (1987 SDL) and am not happy with my heat (150 or so hwy and 160-170 around town). From my reading here and in other forums, this sounds like a typical problem for this engine.

I've already insulated all my hoses, but the problem seems to be insufficient heat coming from the engine (168 hwy, 178 in town).

My first thought was to get a 195 thermostat, but not sure which one to get or if raising the temp on this engine is a good idea in the first place due to fussy aluminum heads.

Just wondering if anyone else with one of these 6 cyl beasts had any ideas.

Thanks!

I've got an 86 sdl, first I've heard the engines have problem producing enough heat. I have a 30 FPHE before the two filters. I also, just because I had a couple used on previous vehicle, installed a H50 HE on return line. Seems to be working haven't had clogged filter since installing HE on return line. Now as to what the temps are reaching I have no idea as I don't have temp guages set up, other than what came on car. I have some insulation, could probably use more. I did do away with fuel thermostat and was running vegoil through that loop but have since bypassed that as it seemed to give a couple more spots for air leaks and the fuel line was getting too complicated. For the plastic primary filter I was using a screen filter with 5 micron felt as element but it tended to leak, so I replaced it with a remote spin-on filter head, even put vacuum gauge on it, no leakage. Waiting for filter to clog up but doesn't seem to want too, laying that off on the return line HE. Am using oil filters reversed to avoid the bypass opening up, with antibackflow sabotaged seems to be working. Am waiting for filter to clog so I can try a 10 micron hydraulic return line filter that doesn't have a bypass, when it clogs it clogs. Don't know if I helped or not but got to rambling.