Hi all, Im in the middle of changing belts,hoses and T-stat and rad.flush on my 82 300D. I want replace the bypass hose that runs from the water pump to the T-stat housing. Do I need to remove the water pump? or remove the T-stat housing? I beleave my water pump is good so I hate to pull it If i dont have to. Also does the T-stat housing have a gasket where it mounts to the head or how does it seal? Will I need a new seal or gasket when I pull either one off? Thanks Tom 82 300D

There is no need to remove the water pump. just the thermostat housing. There is a gasket between the housing and the head. It's a really easy job.

VICTOR REINZ Thermostat Housing Gskt.,W0133-1643897 - PeachParts

COOL!! Thanks for the help. Tom

I need to do the same thing. Sounds fairly straight forward.

Anyone know the torque for the thermostat housing bolts when re-assembling?

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

The 617.95 service manual does not specify a torque value for the housing-to-head bolts. It lists 9-11 Nm for the thermostat cover bolts, however.

Be extremely careful when removing the bolts from the t-stat housing for cover removal. Some of them are exposed to the coolant and all can easily be twisted off, if some time with PB blaster is not taken. I was lucky when I had my incident, as the damage was repaired by an 'industrial strength' welder at the old place of business.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

Thank you for the heads up, will begin the soaking tonight before attempting this.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I have an 85 300sd. Can't find "bypass hose" at Fastlane. Is it under some other name or not in the cooling system list? Thanks.

The bypass hose is not listed on Fast Lane`s catalog. It is a special order part from MB, and they only sell it by the meter. that would be a life time supply.
I called Phill today, and he gave me the part# 900271-042-012, and to put it into the Special Order Parts and Search box on the left side of the Buy Parts page. The price was ONLY $70.00 . dang I only need 2 or 3 inches, not 39 inches (meter).

I did a search on the bypass hose, and according to TANGOFOX it is 42MM I.D. and the dealer sells it by the inch.

I might check our local Hydraulic hose shop on Monday and see what they have.

The hose dimentions are: ID=42mm, OD=54mm, 40mm Long.

Bought a piece of hose from the Hose Shop, gave them the metric size plus they measured the thermostat pipe. It is 1-5/8 inch
Plus two 100% SS T-Bolt clamps. range 1.81" X 2.06"

I was having trouble with the by pass hose leaking, changed clamps, repositioned hose, still leaked. but only leaked when it sat over night and cooled off. when it heated up the leak would stop.

So have new hose and clamps, and the leak stops, . must have scared it.


Charlie ☺

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

I have a 300E 1991 and have the same problem!! But I think I must to take off the water pump to replace the bypass hose.
Am I wrong?

No need to remove the water pump.
I am trying to replace the gasket for the water pump housing and I have yet to get it off. the water pump is still attached and the bypass hose is off as well. I only needed to removed the t-stat housing to remove the bypass hose. Very easy.

Getting the bottom bolt for the water pump housing is what has me stumped. I am trying to avoid removing the balancer and crank pulleys. The handy little notch in the balancer is not enough (it seems) to get the bottom bolt loose, never mind free.

Any ideas ?

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83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.

Phil sold me about 8 inches last year. Ask if he will cut it for you...

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"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy"

Current
Monika '74 450 SL
BrownHilda '79 280SL
FoxyCleopatra '99 Chevy Suburban
Scarlett 2014 Jeep Cherokee
Krystal 2004 Volvo S60
Gone
'74 Jeep CJ5
'97 Jeep ZJ Laredo
Rudolf ‘86 300SDL
Bruno '81 300SD
Fritzi '84 BMW
'92 Subaru
'96 Impala SS
'71 Buick GS conv
'67 GTO conv
'63 Corvair conv
'57 Nomad

This was posted back in April.
The M103/104 is a whole different animal- to replace it, either the water pump or the cylinder head needs to be off.... your choice

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

I cant recall ever having had to remove the housing itself, is it cracked? theres a gasket between the waterpump and the housing thats replaceable if thats whats leaking on yours. The balancer will need to come off to get that last bolt out.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

That's the problem I have now. I had no leak (but a very ugly, rotted-looking bypass hose) so I changed the hose and installed a new gasket (there was no gasket before btween the t-stat hsg and the head) and now I have a leak.

I'm waiting until it warms up to do anything else. I just top off the coolant every now and then.

So the balancer needs to come off to change the water pump? I didn't know that...wait were you still talking about a 123 diesel?

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now