Was looking at my 83 300D today and saw something that kind of disturbed me. I was looking at the thermostat housing and checking hoses. I saw a hose, about 3 inches long that came out of the bottom of the thermostat housing with two hose clamps on it. This hose looked like it was original to the car (i.e. 30 years old!) It is not leaking, but it looks very worn on the outside and felt as hard as a rock.

Looking at it, it looks like changing it would be a royal PITA. Anyone ever changed this hose before....if so, how did you do it?

Thanks,

Glenn

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

You can access that hose by removing the water pump housing from the engine.

Drain system
Fan off
Belt off
Pulley off
Water pump off (carefully those bolts break super easy)
Housing off the block
Swap the hose piece
Put it all back together.

Of course this is a classic MAW...
MAW change the water pump
MAW flush the cooling system
MAW change the thermostat

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

I'm going to do the same job soon. It looks to me like it would be much easier to remove the thermostat housing rather than the water pump housing.

__________________
'81 300SD

Yes, remove the thermostat housing. Still possible broken bolts.

I have performed this job. The bad part is if the metal neck you clamp the hose onto has corroded so badly that it melts away. Clean-up the neck with a slow cutting file or sandpaper and if necessary, fill in BAD pits with JB Weld.

I bought a pre-cut hose from a source which shall not be named; I have noticed others on this site have determined the hose size and you can buy a generic hose of that size and cut your own piece.

__________________
Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles

Yeah funny bit of hose that one - if I remember correctly the pre-cut lengths at the dealer are massive and very expensive.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

That is what I had to do.
If you do the JB Weld thing be really get in the pits and clean down to the shiny bare Aluminum or it will simply corrode between the JB Weld and the Aluminum.
I filled in the Holes with JB Weld and as I was doing that wrapped over the filled Pit with Tape to try to preserve some of the tubular OD and it allowed Me to do all the Holes and one time.
Peeled the tap off and went back and filled areas the JB Weld did not fill in and did the filing and sanding after it all cured.

__________________
84 300D, 82 Volvo 244Gl Diesel

Consider silicone heater hose on ebay. It is pricey, but should last almost forever. I replaced a similar short hose on my Mopar slant six engine that goes from the head to the water pump. The silicone was flexible enough to work it on without removing any parts. whereas standard heater hose was a b*** when I did that job 34 years ago. I haven't done similar on my 300D's so don't know the size. I did remove the aux heater pump on my 84 300D and replaced w/ 5/8" silicone hose. Also comes in flashy colors.

Think this hose, is one of them...if it's not broken don't fix it...ordeals...I personally really doubt this hose no matter how old it is will ever just explode....if its starts leaking then I would tackle it...until then, I don't need the headache of it

__________________

The hose on my 83 300D with 297k (now sold) had the original hose which looked really in bad shape, it was all puffed up and was begging to be replaced. It was not leaking so I left it since it's such a PITA job. I did have a coolant level sensor so I would have caught it before overheating the engine if it did leak.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I've done the coolant return hose too. Napa was the only place that had straight radiator hose but it was only about $6 per foot. It only took a few months before coolant was permeating through the hose. I've got another 9 inches of it but instead of using the same hose, I think its time to hit up the dealer for a hose that'll last. As for the job itself, it's easiest to remove the thermostat housing from the block but remember to replace the seal. I think I had to remove the EGR tube as well. Don't forget to purge the air from the system once you're done (have car facing uphill with cap off expansion tank and add coolant to line while engine is running).

Send me a PM. I just bought the "coolant bypass hose" for < $5. Had to go to another source because Peach only carries bulk for > $35. Also had to buy vacuum pump elsewhere for $100 savings because couldn't get price match worked.

I'm sad because Peach gets "last look" but didn't get the business.

__________________
85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

a couple of months ago. Only had to remove the thermostat housing. Nothing else removed.

Purchased kit from XXXXXXXXXXXXXXXX. Includes correct length of hose, new clamps and instructions. Inexpensive.


DON'T work around the software ban of parts sites

1-5/8" fuel tank filler hose is a perfect fit, and NEAR INDESTRUCTIBLE.

It's what we used on JAYBOB's car.

__________________
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!