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mholbrook 08-26-2003 02:56 PM

My 83 300TD-T runs in the cool morning at about 85 degrees which is normal as I am told. On the way home in the heat of the afternoon with the AC on and driving about 70-80, the heat will sometimes go as high as 100 degrees but usually stays a little below like at about 97 degrees. Less than 1 needle width from the "line with no number".

I have been told this is normal but it does bother me. If I get off the freeway and drive around town for a little while, the temp goes to about halfway or slightly less between 100 and 80 degrees. That would seem normal to me but it is the higher speed runs on the freeway that bothers me.

Am I just worrying for nothing?



R Leo 08-26-2003 03:38 PM

My two 617.652 engines have completely different temperments (no pun intended..) so, you may simply need a flush and fill. Or, it may just be the way things are.

For reference, my TD runs 'cool' almost all of the time, with the A/C on and at highway speeds, the needle is at the top of the eight in the 80C marking. Extended idling in the afternoon Texas sun will run her halfway up to the 'no number' mark at 100C.

Under the same conditions, SWMBOs 300D almost always runs at a point just about 2-3 needle widths below the 'no number' mark and will creep up close to the mark after lengthy idling. Instructions to SWMBO is that if the needle goes above the 'no number' mark, shut her down immediately and call for assistance.

Later this fall, I plan to flush the systems with MBZ citric flush and replace all hoses. MBZ coolant will go back in when I'm done.

I'll be interested to see what they both do after that service.

mholbrook 08-26-2003 04:03 PM

OK, after looking at some archives, it appears that my heat situation is normal. I think I will flush everything out before the next summer hot spell comes along.

By the way, at idle, my temp does not go high, remains about 85-90.

Thanks for the imput.

ForcedInduction 08-26-2003 04:56 PM

Even with my 617.952 nailing and a slightly too small electric fan for main cooling, those tempretures sound normal. I have found highway driving at 3K rpm, 65mph, and 7PSI are best. It will stay right at 80-85 without any problems. If I run at 10PSI it will jump to the 100*C mark very quickly. Quite a fine line.

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