300TDT - Removing Exhaust Manifold - PeachParts Mercedes-Benz Forum

sashal · #1 12-31-2009, 01:08 AM

I am trying to replace my exhaust manifold gasket. According to the factory manual, I need to remove the intake manifold and turbo along with the exhaust manifold. Step 5 in the service manual says to remove all three together. Here are my questions:

1) Do I really need to remove all 3 out of my car? If so, they sure neglect to mention all of the many hoses, pipes and components that also need to be removed to make this possible.

2) Does this mean that on my car in order to replace the exhaust manifold gasket, I will also need to replace the intake manifold gasket (since a lot of times once you take off a gasket, it doesn't seal right when replaced. Another possible option is leaving the turbo but replacing the turbo-exhaust gasket as well.

3) If I have to take the turbo off, it also seems like I should be removing the two "hose clamp" bolts that are on each end of the accordian pipe on the turbo. It seems like the manual recomends removing the bolts behind this but that will make taking all three components out together impossible since those bolts face front to back and the exhaust bolts/studs point to the right.

Thanks for your help on this matter. I was able to get all 7 exhaust manifold bolts off and I thought that I was moving along nicely but these directions are a little confusing.

Sasha

layback40 · #2 12-31-2009, 02:36 AM

Sounds like you didnt pull the motor out Sasha.
We dont have turbo w123 300d's in Australia. If I needed to replace the exhaust manifold gasket, I would take the inlet off as well. I think, based on experiences with other turbo's I would try & leave the turbo attached to the exhaust manifold. Replacing the inlet manifold gasket is good insurance as with the turbo, you run reasonable pressure in the inlet manifold.
If you wish for a cheap & nasty fix up, you could try reusing the inlet manifold gasket with RTV on it. I dont recommend it though in case it leaks & you would be back doing this all again.
All the pipes etc are a PITA but if you just go 1 step at a time it isnt that bad. I always find its better to get an extra few things out of the way.
Did you find your oil leak?
Good Luck!!

Sev · #3 12-31-2009, 05:09 AM

Quote:

Originally Posted by layback40

We dont have turbo w123 300d's in Australia.

send us some of your w116 6.9's--i'll send you a few w123 turbos in exchange

charmalu · #4 12-31-2009, 05:31 AM

The intake/exhaust manifold gasket is one in the same. not 2 gaskets.

remove the 3 nuts holding the down pipe to the turbo.
remove the turbo oil supply line. 2 bolts on the turbo,one at the back of the head, and the one at the oil filter housing. just let it hang loose.

you got the 7 nuts off the manifolds, did you also get the one under the turbo? there is a short bracket bolted from the turbo to the engine mount arm. 17MM. that`s a fun one.

remove the boost line off the rear of the intake manifold.

remove the turbo drain tube, 2 13mm bolts,

pull the intake/exhaust and turbo off together, takes a little wiggling.

I have loosened the down pipe at the transmission mounting bracket so the pipe will drop back to give me room. usually the down pipe is stuck to the turbo. I use a brass drift and give it a whack with a hammer.

hope this helps, Iam doing this from memory at 2:30am.

Charlie

layback40 · #5 12-31-2009, 06:58 AM

Sev,
I have driven 2 w116 6.9's. They go like #*^~ !!!! I know where one is sitting in a shed but the guy wont sell it. There is absolutely no room under the bonnet. Its one car you could not work on 1 handed Sev. One of the biggest problems with them I have been told is that the black box for the fuel control is just behind the headlight & is destroyed in even a small prang. I have been for a ride in an older (1968) tombstone headlight merc, I think it had a 6.9 as well it wasnt any bigger than a w123 . I think the badge on the back was 280S 6.9 , it was much quicker than the later ones. They wouldnt be any use to you Sev, you dont have any roads near you long enough to get into top gear!!!!!! LOL

Carpenterman · #6 12-31-2009, 09:59 AM

I just did this job to renew the turbo drain seals, replace the starter, and look for an oil leak.

I second the advice above. It is correct that there is only one gasket for both manifolds.

I ordered a turbo removal kit (from I don't remember where--I think it was $39) because I couldn't find the turbo O ring and turbo gasket separately. The manifold gasket they sent me was the wrong one, even though it was specified for my '81 300TD. I had to reinstall the original as I needed the car.

I initially tried to remove the turbo from the manifold but the nuts are very hard to access and the ones I could access were very tight. Just leave it on. Much easier to replace turbo gasket with it off the car.

I was too lazy to loosen the oil supply tube at the oil filter housing and the job still went OK. Think about leaving the air cleaner bracket on the manifold as it is very difficult to get the lower mounting bolt threaded back on correctly.

You don't need to remove the turbo drain from the turbo if you don't want to. It's just a slip fit into the lower tube and comes apart easily when you pull the manifolds. Much easier to renew gaskets with the turbo off the car.

Be prepared for some problems taking the three exhaust flange nuts off. PB Blast the heck out of them well in advance. I rounded one off and had a devil of a time.

Strangely enough, I couldn't find torque settings for the manifold nuts. Haines says "securely". I guess you have to use your own judgment. They were barely tight when I removed them.

The short flex tube with the clamps wouldn't come off my car unless I removed the mounting bracket. A pain to reinstall and get everything lined up and the bolts back in.

Don't forget to locate the flange collar up on the exhaust when you get the short flex tube and bracket positioned. If it has fallen down the exhaust past the starter it will not clear the starter.

If you have a Haines manual it actually has a pretty clear description for removal and reinstall.

Happy wrenching!

sashal · #7 01-13-2010, 08:19 PM

Thanks for all of the responses. It is one gasket for the intake and the exhaust and the bolts that go through the intake manifold and the turbo gasket make it neccessary to remove all three.

The removal job included a number of irritations but was completely do-able.

I am going to try to get it all back together tomorrow.

Thanks again for the replies.

Sasha

snookwhaler · #8 01-13-2010, 09:15 PM

Quote:

Originally Posted by sashal

Thanks for all of the responses. It is one gasket for the intake and the exhaust and the bolts that go through the intake manifold and the turbo gasket make it neccessary to remove all three.

The removal job included a number of irritations but was completely do-able.

I am going to try to get it all back together tomorrow.

Thanks again for the replies.

Sasha

Be sure to clean the intake manifold...

layback40 · #9 01-13-2010, 10:22 PM

X2 for cleaning the inlet manifold. disabling the EGR would help also.