Mercedes-Benz Forum banner

Head Gasket going out?

3K views 38 replies 8 participants last post by  emdcksn 
#1 ·
I just got home and might have a possible problem. I am ready for what I think I am going to hear.

I am flushing the cooling system and after I got home, I popped the hood to check the water level and all was good. I shut the car off and was poking around the engine compartment when I heard a "Fizzing" sound from the rear of the engine and false firewall. I hate to think it but, Head Gasket? There was no oil in the coolant and no water in the oil when I changed it a few weeks ago.

Ideas?
 
#4 ·
Could be one of the small hoses that go into the false firewall area, especially if the flush dislodged something that was barely holding one of the hoses intact.

The heater hoses on my 300SD did that to me, on one of the ~1/2" hoses that make a tight turn and go through the firewall toward the monovalve.
 
#7 · (Edited)
Just got home and found the "source" of the leak. Unfortunately not a heater hose. It is coming from behind the rear manifold in the #5- #6 area. Not surprised with 268k on the clock, but good grief!

It probably was bad when I bought the car and didn't rear its ugly head until it got pressurized. Are there any good write ups for M103 head gasket jobs?
 
#8 ·
Well, it is confirmed. Had my son start it up while I held a shop light on it. As soon as it started, water began to flow from the right rear corner behind the manifold. Once shut down, it sprays water until it is depressurized. I really wish it was a heater hose, but oh well. My son stated, "it just means more wrenching for us to do together"! He's a good kid. Most of the time.
 
#9 ·
so you will have new heads, valve job too and another 200k.
 
#10 ·
Yep. I knew it would be a possibility when I bought the car. A head gasket and everything that goes with it looks pretty straight forward on this engine.
 
#11 ·
I should add, I am sorry that you have to go thru this. I bought an 87 so I could be prepared for this eventuality. I have the heads, cams ready to be milled for a quick swap.
 
#12 ·
It is a bit of a bummer, but I have done it before so no big deal. As usual, new head bolts cost more than the gasket kit. I will use all MB parts of course. My 10yr old is looking forward to it. He has never seen a job like it. The last engine I rebuilt, he was still a baby.
 
#14 ·
The achilles heel of the M103 engine, the head gasket. I guess in a way it's "better" than the heel of the V-8's, the timing chain guides potentially wrecking the engine. I believe one of the PO's had to do mine long ago and other than a slight oil leak mine has been good to go. It's one job I hope I never have to do but I know there is a good write up in the DIY section to cover it and as Louis said, good for another 200K
 
#15 ·
It looks like an easy job in the FSM. I am looking for the DIY for the M103 HG but I am not finding it. Can someone with better search skills help out?

Thanks
 
#17 ·
#16 ·
I have never had any oil loss since I have had the car. Other than replacing guides and seals, what else should I do to the head and or replace before reinstallation? I had the head rebuilt on my last overhaul because I was doing the entire engine.
 
#23 · (Edited)
Got started and rolled on until I ran out of light (garage is full of woodworking tools). I discovered that the head bolts take what looks like a 12pt allen socket. Can someone please fill me in on what the tool is and what size I need so I can find/order one?

The FSM doesn't say to do it, but this would be much easier with the radiator removed.

Thanks
 

Attachments

#24 ·
Found the Head Bolt tool on Snap-On's site. They are called a "Tri-Square Bit" and Pelican Parts says I need a 12mm. I LOVE getting new tools. Even if I am only going to use it once or twice.

Next question. They come in a couple of different lengths. Stubby, standard and long. I am leaning toward stubby-standard. The shorter length should mean less twist.
 
#27 ·
I have been running M1 15w-50 since I bought it. Hopefully it is helping clean up the inside. I removed the radiator and everything off of the front of the engine today except for the Alt and AC compressor. As long as the cylinders look good, I'll have the head gone through and start putting her back together. Just waiting for the 12mm Tri-Square bit socket so I can remove the head.

When I am done, the front will also be renewed.
 
  • Like
Reactions: wooky_chew_bacca
#29 ·
They are not necessarily more delicate, the the profile pic shows there is quite a bit of contact surface.

I have a similar 10 pc 4mm - 18mm spline CRV set (Neiko). Online, $23 - 25 shipped is a good price.
The quality for use on hand tools is pretty good, just make sure the bit is completely seated / inserted (no dirt in there)
Lower sizes are 1/4", biggest sizes 1/2" drive, 8, 9, 10 & 12 are 3/8 drive, so I would recommend a decent 3/8 breaker bar, plus a torque wrench to be able to evenly tighten to spec.

Anyone looking over the head will check for warping.
 

Attachments

#30 · (Edited)
Thanks, I was planning on getting a 1/2" drive socket and I do have the necessary torque wrenches and breaker bars. Do you think a set of ARP bolts would be over kill? They don't list anything for Mercedes on their website so it would have to be a custom set.
 
#32 ·
A Mercedes mechanic would know.
Off the top of my head I would be pretty sure about differential.
A single of similar quality bit would be about 8-10 bucks + handling and shipping.
So to me taking a set made sense.
Also, these type fasteners can be found on every Mercedes made after 1985 (before was allen).

Usually the manual will tell the type and sizes of tools needed for specific jobs.
 
#33 ·
Getting ready to remove the head now. Is TDC for #1 /#6 the long hash mark to the left of the "T" on the Damper? The picture in the manual is a bit fuzzy.
 
#35 · (Edited)
Everything is detached from the head except for the chain guide pin and the tranny dipstick tube. Hercules must have tightened it down and rounded the inside of the bolt in the process. If I can't figure how to remove it, I will have to resort to cutting the bracket and replace the filler pipe. Other than that and needing more free time, she is coming right along. Having three vehicles sure makes it a nice unhurried job.

I did choose to separate the intake and exhaust manifolds before removing the head. The head is going to be overhauled and the rest will get taken care of as well.
 
#36 ·
I have been scouring the FSM and searching through old posts and can't find the intake/exhaust manifold torque specs.

Anyone got them?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top