Mercedes-Benz Forum banner

Big Seafoam OOPS, 79 300TD

2038 Views 13 Replies 4 Participants Last post by  reinventthewheel
Ok, so my last car was a gas VW Jetta and when I got it, it had an incredibly dirty intake manifold. I did a few seafoam treatments through the vacuum lines and it worked miracles.

I just got a '79 300td (non-turbo) and there's been a lot of blow-by. The air filter and housing is full of dark oil, and the car smokes much more than it should.
My thought was that since I was dealing with a similar problem, I would turn to a similar solution. I sucked a half a can of seafoam through the thin vacuum line coming off of the thick one that leads to the brake booster.

Since the big cloud of smoke didn't come out afterwards I just started to look up Seafoam treatments on these vehicles and found all this scary stuff about hydro-lock. Yikes.

I've only driven about 1/2 mile since doing the treatment, but I'm supposed to be driving almost 300 miles tomorrow (hence the desire to clean out the intake before getting on the road).
SO! Did I fuck things up? What do I do to fix it?
Also, how can I clean out the intake manifold? Will seafoam in the fuel do the trick?

1 - 4 of 14 Posts
when gasoline engines use intake as a source for vacuum -diesels have mechanical pumps for it.
sounds like your pump is very clean by now?
Those engines have engine ventilation going into the air filter housing, so oily intake is perfectly natural. High blow by is not. How bad is it? Will it blow oil cap off?
There is Moly brand diesel purge that does a wonder on older engines. Start with that.
I don't remember where the vacuum pump blows the air out, but what is done is done. I can only hope the SF being petroleum will not dissolve the pump diaphragm.
Blowby can be roughly measured by lifting force of gases at the oil fill. My diesels will not blow a paper towel lay down on the hole, than you can put a piece of cardboard and see if it will stay, in extreme blowby the reversed cap will get blown off.
Now the oil all over the filter is not really precise description. I used to have turbo version and I can only assume your engine is having similar system. The crankase gases go inside the air fuel box where there is oil separator with wire filter in it. The excessive oil should drip at the separator and special tubing takes it back to the cranckase.
The system needs to be clean and well connected. I still remember that assembling the air box and making sure the drip tubings go into right place was quite a trick and have seen lot of cars with that tubing dangling loose under the filter. Also orings replacement on the tubing is often neglected.
See less See more
Start with diesel purge and take it slowly. If the engine was neglected in the past, some things might be irreversible, so don't expect miracle in the bottle.
Your engine was design to run on dino oils. I do oil testing for last few years and shell Rotella seems to be the best on the market. It comes in dino and synthetic version. My Ford diesel loves T6 synthetic and I will switch my Mercedes diesels to it as well.
All the oil flushes have been proven more or less to be a kerosene mixed in different proportions. Same is Sea Foam. Just do earlier oil change if you feel it is necessary.
Filters are oversize on those cars, so unless you see lot of sludge, don't worry about replacing it before oil change.
get used to fly. You should see what he did to his real plane, that was on the background of his old signature picture :D
By taking slow I mean don't expect the car to start burning the rubber after the purge, or oil change.
1 - 4 of 14 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.