Question about coolant bypass hose.
 

On my 1988 300E, the coolant bypass hose is leaking. The hose leads to a metal pipe that leads to the cylinder head. Can this be removed? I think it may be leaking from there as well.

Also, I have the dreaded slight leak from the top front timing cover. Is the best stuff to use still the special MB sealant?

Steve

Run a search under "bypass hose" and you'll find alot of information. One thread in partucular you should read is called something like "The little hose that could".

Some people say that they have replaced the bypass hose by sneaking it into the tiny crack between the two metal tubes. The crack width is about 4mm. The majority say the water pump must come out. Having just done this, I agree with the majority. If I were to do it again, I would attack it as follows. Not all of these steps are absolutely necessary, but I found them helpful.

Remove the air filter, its housing, and the air intake tube. Remove all hoses connected to the radiator. Unclip the fan shroud and the radiator. Lift out the radiator. Lift out the fan shroud. Remove the fan blades. Remove the serpentine belt. Remove the fan clutch plate. Remove the fan pulley. Remove the water pump pulley. Remove the Power Steering pump pulley.Remove the Y shaped tensioner support bracket. Remove the tensioner shock absorber. Remove the tensioner while unscrewing the tension adjustment nut completely. Unbolt the Power Steering pump including the long bolt that goes up at an angle into the AC compressor pump. Push the Power Steering pump to the right to get it out of the way. Remove the idle control valve. Unbolt the water pump (have a wide variety of sockets, wrenches, and extensions both regular and flexible available). That's it for the removal. Now put it back together. Enjoy!

Actually, it's time consuming but not unpleasant. Many advocate the replacement of other parts as long as your in there. Check a prior post of mine where in I ask exactly that question and read the responses. I have no advice for your other question.

As part of the minority...
 

and lazy. This is the way I did it. Cut the old one (this is the point of no return), the trick is to get the hose from the dealer (aftermarket is too rigid), use some type of lubricant and go for it. Start with the small end, the other will just follow.
If it does not work follow the procedures explained above and do it the old fashion way.
Good luck!:cool:

If you're gonna remove and reseal the front timing cover, then might as well go the way that Hans described since you'll have all that clutter off -- and yes, the MB sealant, although pricey, is still the best stuff.

IF you're lazy like J.H. and I :D :D try his method. Buy 2 hoses though just in case you mangle the first one. They're pretty cheap.

Good luck!

~Paul

_________________
'91 300E, 209k miles

Can the metal pipe that goes from the rubber hose into the head be removed? Is there and o-ring in there or something?

Thanks,
Steve

No!
 

:(

Yes. And no. On the M103 engine that tube can be removed. According to MB, you need to trim the tube near to the engine block, and then crimp the tube with a punch, bending and effectively collapsing the tube. You then wiggle this collapsed tube out, smear locktite on the new tube and insert the new tube as far as it can go. If you are envisioning this as a short cut to replacing the bypass hose, it almost certainly won't work as the water pump will get in the way when trying to insert the new tube. I have no opinion regarding other engines.