Oil leak at oil cooler connector.
1999 E300 Turbo Diesel




This is the oil cooler.
The leak is between the large rusty color nut on the left and the aluminum connector on the right.
The leak is between the two parts.

Location - Driver's side North America.
Between the front wheel well liner and the front bumper.
The two lower plastic shields / covers must be removed.
As seen from below.

I have put a large adjustable wrench on the rusty nut and it won't budge. Not interested in twisting it off.

Presently I have sprayed it with Kroil penetrating oil.

Ideas please . . .

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250

Kroil every day for a week, then loosen and re-tighten.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

When you are ready to attempt turning the Collar find some way to use 2 Wrenches; one on the Hose Nut/Collar and one on the Fitting the Nut Collar screws onto.

You might have to thin the head of the Wrench in order to fit it between the Nut and Oil Cooler Housing.

If the Oil Cooler Hose is in Poor condition and you decide to change the Hose you can cut the Hose Nut/Coolar Length wise (if possible one cut on each on opposite sides). And then split the Nut/Collar in two pieces and avoid having to screw it off.

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84 300D, 82 Volvo 244Gl Diesel

Cut myself to the bone the other day so I took it to my Indie, who even though it had been soaking in kroil sheared off the fitting at the oil cooler.

Question, I just want to weld the lines closed and take the cooler out of the equation.

Estimated repair $1300 here.

Ideas please

__________________
1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250

I would not recommend bypassing the cooler... your turbo will cook your oil in short order...
best repair is new lines, and a replacement cooler, the fitting on the cooler MAY be replaceable... or you may be able to weld on AN fittings... and adapt to the existing hoses.

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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 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Indie must not have had a back up wrench on the fitting. Not good. Don't take the oil cooler out of the system. Buy a used one or in a pinch even an aftermarket one.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Inclined to agree BUT with a temperate climate and improved synthetic oils it just might work. At 180,000 miles and the proper repair is just worth about 1/3 of the car and rust is starting to attack.

__________________
1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250

The effort it will take to bypass it is roughly the equivalent of installing a used or aftermarket cooler.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

$1,449.99 later and it is fixed. Not a bit happy

Unrelated/related problem?
After 1 stop on the way home after a normal start the glow plug light would turn on for several seconds then off for half a minute and back on again . . . kept repeating.

Also lamp out will come on (reasonably normal, on the next start all is usually well) today after pressing the hide button it would light up lamp out and after reset light it up again. Sometimes it would take several seconds others a half minute to repeat.

Just took it around the block and glow plug light normal but lamp out repeatedly turned on.

Thinking this could be voltage related I threw the charger on a 3 year old battery and found it charging a 50% of the scale.

Going on vacation tomorrow. Usually it waits till then to break down

Ideas please . . .

__________________
1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250

From post #3
"If the Oil Cooler Hose is in Poor condition and you decide to change the Hose you can cut the Hose Nut/Coolar Length wise (if possible one cut on each on opposite sides). And then split the Nut/Collar in two pieces and avoid having to screw it off."
This would have saved the Oil Cooler from damage; maybe this will help someone else in a similar situation.

I know it seems like I am rubbing Salt in the wound; but the fact is We all make decisions that have bad outcomes.
And, after it is over with We see that if We did things differently the outcome would have been better.

I also think what Kerry said in post #6 must have contributed. I know on the 617 at the Oil Filter Housing there is a similar Brass Colored Fitting between the Hose and the Housing. I had to grind and thin a Wrench to get it onto the Brass Colored Fitting.

Apperently the Mechanic did not have a thin Wrench or did not want or even think about grinding and thinning a Wrench.

If the Mechanic has done that it would have kept a lot of the force of rotation from reaching the that Aluminum Block.

It also looks like it if done carefully the Fitting could have been cut through, the Cooler Removed and a new fitting put on. You would have needed a New Oil cooler Hose as a piece of the Fitting would have been left inside.

Wishing you better luck with your Glow Plug issue!!!

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84 300D, 82 Volvo 244Gl Diesel

Thank you Diesel911

I did tell them and without the finger injury I would have been OK as a DIY. In summary I had read all or most of the previous posts.

I think the glow plug issue will be resolved by a full battery charge. It is still charging at a 3 on the scale. I suspect they had the door open more than closed and ran the battery down. I find that these electronic cars like a full charge to keep them really happy. Glow plugs are around 2 years old and they should be fine. The GP relay or OVP relay could be suspect?

Off to NYC tomorrow on vacation.

__________________
1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250

Wow. That is outrageous.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13