I have a friend of a friend who gave me his 87 SDL to take a look at.

The car SEEMS to be very well maintained.

The info I was given was that it overheated once, and was using a little coolant. They put in some miracle bars leaks, or whatever kind of goo, and it stopped.

That's about all the info I have on the car.

What I have observed:

The auxillary fan in front comes on immediately, even when the car is cold.
The radiator tank (resivoir tank) has a "slant fin" aftermarket radiator cap. You've seen the kind, it has a strange little locking lever.
The temp when driving never gets lower than 85. A short burst on the accelerator.... like a half mile, gets the temp up to the 95 to 100 range.
Prolonged high power applications will get the temp to about 105.

What now? Do I attempt a citrus flush?

Ideas?

JP

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1985 300SD
2001 Toyota Tundra - soon to be replaced with diesel truck
2006 Honda CRV

I'm not an expert on this engine, but the first thing I would do is get the correct radiator cap and see what happens.

This product usually causes all kinds of problems within the coolant passages of the radiator due to the fact that it's designed to plug leaks. So, my guess is that the radiator is compromised and all the citric acid flushes in the world won't correct that problem.

But, the flush is cheap........give it a try.........you never know.

Furthermore, cleaning the outside of the radiator thoroughly with condenser cleaner, with the radiator removed from the vehicle has been known to help the temperatures significantly.

Brian-

In your opinion... a car that cools, but has wide temp swings.... like the 85 to 105...

would you just "run it" and not worry about it?

JP

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1985 300SD
2001 Toyota Tundra - soon to be replaced with diesel truck
2006 Honda CRV

The SD swings from 81°C. to 100°C............downhill at speed........to stopped in traffic with the a/c on.

The SDL does basically the same thing.........getting up to 105°C. on a heavy upgrade with the a/c on.

You don't see me worried..........do you?

I'll bet that both of them have fan clutches that are toast........but.......I'm not dropping $250.00 to reduce temps by a few degrees.

Brian-

Thanks much.

That's one thing to check off my "to do" list on this car.

Now.. what's up with the fuel system.

I went looking for the lift pump... and there are 4 lines?!

I'm going to replace the prefilter. But where do those lines go? I don't see a pump to rid the system of air.

JP

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1985 300SD
2001 Toyota Tundra - soon to be replaced with diesel truck
2006 Honda CRV

Yep, correct, it has no primer pump. If you get air into it, you've got to crank until you get it out.

If you change the secondary, make sure you fill it with fresh fuel........right to the top.......before you secure the bolt. This is not easy to do because of the location.