Well it's not the brakes. The slight rise is from the prior application I believe. Whatever it is insignifigant. The main thing is there is not one wheel or rotor that stands out temperature wise. When I check with an ir gun I usually just hit the rotor.

Location of the bolt that covers the injection pump inspection hole is in the archives. Just look up timing the 603 for the pictorial location. I have not had a 603 and the check in my mind is just in case the pump is far too early.

This would result in more fuel and hotter cylinders if too far retarded for the same performance and less generated heat possible than with correct timing. Resulting in potentially lower fuel milage as well. Most engines would not produce any noticeable increase in heat but your model is almost marginal in the cooling ability by design. I wonder if there were any changes to sell this model in the middle east?

Also while we are at it be careful but after a good run make sure the oil cooler is really hot. your ir gun should substitute for a burnt finger. If for some reason the thermostat for that in the filter housing was not opening the additional heat from the oil may take the cooling temp high.

You should read in the archives when to expect that circuit to be circulating. The oil does remove substantial heat from the engine through the oil cooler in my opinion. For your engine to be functioning well everything has to be working well that has any effect upon the cooling circuit.

Again I do not really expect you to find anything but these things should be checked to remove any remote possibility and they are very easy to do. I guess what I am suggesting is basically covering all bases before speculating on what is left. Or what ever other changes might be worth consideration. Especially those that do not require a lot of money and effort first.

For example I have to wonder what the results might be of using a slightly lower thermostat or a good cleaning of the block passages. As you are all too well aware this engine really does not seem to like running at even slightly elevated temperatures. If I were to consider a good chemical internal block water passage cleaning. I would not leave the new radiator in the circuit while doing it. Everythjing has to be considered as these cars are so old.

The issue with the temp is the same thing that was happening to mine.


Had I listened to all the "experts" here, I would have spent the same amount of money you did with no results. Most said burping, etc.

The answer:

A bad clutch on the cooling fan. $135 on ebay for a genuine MB clutch and the problem is solved!

__________________
1987 SDL. The best there ever was.

I have the same situation. All fans working as they should, new water pump, new thermostat, new fan clutch (metal blades), new radiator...same thing. I am in Florida and it gets pretty hot. Mine will be at 90, right in the middle when on highway or when the A/C is off. With A/C on, it will be above. Mine typically does not get past 105, MAYBE 110 when I floor it. Same result with ALDA in or out. My fuel mileage is also low...20-25, but usually right at 22-23.

I have put 30k on the car without any head/head gasket related issues. I also have to add a bit of coolant every few months. I think it is normal. I have an 80 degree thermostat in. Prior to me getting a new Fan Clutch, I was experiencing even high temps when I was not cruising at 40+ mph.

__________________
1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Bump.......

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1985 300D, 250k
1980 300SD, 180K

jonbob...

Are you saying the fan clutch fixed your problems?

__________________
1986 300SDL ~300,000 mi.
1989 560SEL ~175,000 mi.
2011 F-150 ~37,000 mi.
1953 M38A1

I still consider my temps high at times, so no. However, prior to replacing fan clutch, whenever I was stopped or in stop and go traffic it was steadily rise to 110-115. Once I got going 40 where air was flowing through radiator, things improved. So yeh, now my max idle/stop and go temp is 105, and I see 110 only when I full throttle it for a spell and it's very hot outside.

And using a 606 clutch or clutch and fan is MUCH cheaper and is apparently a direct drop in.

__________________
1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

are you certain the fan blades are oriented the correct direction? of course it spins the correct direction, it's attached to the serpentine belt, it has no choice but to spin that direction, but if the blades are oriented the wrong way, you could be blowing instead of sucking.
just something to check.
sounds like you are searching for ANY reason for the heat.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I had the same problem with my 1987 300SDL, I replaced both hoses, thermostat (drilled three holes), Radiator, citric flush multi times new water pump. Then I checked the fan clutch and it was bad. I ordered one from Phil, and replaced it. Know I can have my A/C on in stop and go traffic, and she sets just a hair above 80 C.

But they are right, the cooling system on these MB aren’t the best. I would expect a larger more powerful electric fan upfront.

__________________
Professional greasecar installer
Austin TX


98 Jetta TDI with grease car kit + veg-therm (totaled)
87 MB 300SDL running on B99 / greasecar kit + 30 fphe
www.austingreaseguys.com

Just to update on this issue...

Thanks everyone for your help and ideas. The problem ended up being cracks in the original #14 head.. at first I thought about replacing it with a used one, but decided to just go with a new #22 and eliminate it as a concern going forward. The car is in such good condition otherwise that it would have been wasteful to junk it, and I figure it should now last roughly till my kids are in college, lol. The repair will be right around $4k.

Anyway thanks again. Hopefully some of your suggestions end up being the fix for someone else having similar symptoms.

Glad to hear the problem was solved. The important thing for others to remember. Is that I believe there were no other indications of a cracked head other than the operational temperature was generally too high to be comforatable with.

Tough call to pull the head if there is nothing else indicating the fault. On the other hand you pretty well had already covered probably all other possible external faults.

It is a real shame mercedes did not get a good reliable head casting in production with the 603 type initially. The result has been a lot of grief for a lot of people.