M103 Best Motor Ever - Page 4 - PeachParts Mercedes-Benz Forum

#46 07-23-2009, 01:00 PM

I'm sure that 10% Ethanol is digested just fine. The question surrounds what materials it attacks on the way to the stomach.

pawoSD · #47 07-23-2009, 01:54 PM

Quote:

Originally Posted by LarryBible

Don't make a huge bet on the valve seals being a cure all.

Yes the belt tensioner and water pump are a pain, but these engines have many other, more important redeeming qualities. I don't consider the M103 to be the end all masterpiece, but it is a very good engine.

Why not?

I sure hope it at least really reduces oil use....so long as it stops fouling plugs I'll be happy. Currently about 2 plugs get fouled after about 1000 miles of driving....the others look fine. The valve seals are original at 140k....so they're probably stone hard. Hopefully it improves things!

Hit Man X · #48 07-23-2009, 02:43 PM

Quote:

Originally Posted by pawoSD

Why not?

I sure hope it at least really reduces oil use....so long as it stops fouling plugs I'll be happy. Currently about 2 plugs get fouled after about 1000 miles of driving....the others look fine. The valve seals are original at 140k....so they're probably stone hard. Hopefully it improves things!

I agree w/ Larry. The seals won't help like you think, you need to yank the head. BTDT.

I was once told the valve guides on the M103 are very soft causing them to wear quick.

pawoSD · #49 07-23-2009, 03:19 PM

You think the guides would already be really worn with only 140k on it? I read on here that the guides usually last till around 200k ish before needing replacement.

I guess I'll have to hope the seals help, I have no $$ to be pulling the head.....I still need to fix my SD!

Hit Man X · #50 07-23-2009, 03:54 PM

Quote:

Originally Posted by pawoSD

You think the guides would already be really worn with only 140k on it? I read on here that the guides usually last till around 200k ish before needing replacement.

I guess I'll have to hope the seals help, I have no $$ to be pulling the head.....I still need to fix my SD!

You fail to recall it's not only mileage that wears a motor, but HOURS.

The seals are easy, you should have done them yourself. I did mine in a few hours, waste of time but I did them.

Fix one to have a 100% vehicle then you can afford to have the downtime with another... versus having two 50% vehicles.

pawoSD · #51 07-23-2009, 03:58 PM

Quote:

Originally Posted by Hit Man X

You fail to recall it's not only mileage that wears a motor, but HOURS.

The seals are easy, you should have done them yourself. I did mine in a few hours, waste of time but I did them.

Fix one to have a 100% vehicle then you can afford to have the downtime with another... versus having two 50% vehicles.

I suppose hours could play a role....

I didn't want to do the seals because I don't even have an air compressor or anything....I didn't want to risk anything going wrong either.

Future jobs like this I will (and usually do) do myself....this one it was just easier to have done.

After next week my SD will be back at 100%...I am pulling the motor and doing the trans swap early next week....and technically the 300E should be by this evening.....if all goes well.

dynalow · #52 07-23-2009, 05:00 PM

Quote:

Originally Posted by pawoSD

I suppose hours could play a role....

I didn't want to do the seals because I don't even have an air compressor or anything....I didn't want to risk anything going wrong either.

Future jobs like this I will (and usually do) do myself....this one it was just easier to have done.

After next week my SD will be back at 100%...I am pulling the motor and doing the trans swap early next week....and technically the 300E should be by this evening.....if all goes well.

Had my seals done about 4 years ago. IIRC, I had about 75,000 on th eodo then. Seals were less than forty dollars. Few hours of Indy labor. 200.00 or so out the door. Stoped my consumption problems.

And I recall reading a while ago that the guides on the 103 will wear sooner than you might think. Check these threads out.

Insist on new valve guides on M103?
M103 Valve Stem Seals Done!

pawoSD · #53 07-23-2009, 05:12 PM

Mine is a 1990....so it should have the upgraded (stronger?) guides....I'm not super worried, the engine runs flawlessly aside from some oil getting on the spark plugs in cylinders 3 (barely) 5 (moderate), and 6 (a bit more than moderate)....As long as its good enough to stop plug fouling, then I'll be happy. Otherwise I will go insane.

#54 07-23-2009, 05:37 PM

Quote:

Originally Posted by pawoSD

You think the guides would already be really worn with only 140k on it? I read on here that the guides usually last till around 200k ish before needing replacement.

I guess I'll have to hope the seals help, I have no $$ to be pulling the head.....I still need to fix my SD!

It was the first year or two of the M103 engines that seemed to respond to valve seal replacement. The later engines have the upgraded seals starting out.

Hit Man is offering some really solid advice in suggesting that you get one car to 100% then attack the other.

Pulling the M103 head is a job, but it's not an insurmountable job. Actually it goes quite well. I prefer to leave the intake manifold in place and work with a long extension from underneath for a few of the bolts. For the M104 it is best to leave the intake attached to the head and lift them off together.

The bottom of these engines are virtually bullet proof. This means that doing a good job on the head with new guides et al, will give you virtually a new engine. IMHO, doing the head and doing it right is a VERY worthwhile thing to do on these cars if they need it and it sounds as if yours needs it.

ps2cho · #55 07-23-2009, 06:36 PM

I can tell you from my experience rebuilding my 300TE's head, it really wasn't that bad.
I have never done it before, but with all the info I needed in front of me (thanks to many forums with tips + walkthroughs + pics)...it was not bad at all. With all rebuilds of course, there are bound to be surprises.

I have gone about 6k miles since the rebuild and not a single drop of oil used. Seals/guides are perfect, head is perfect. Beautiful

Just gotta resolve a few CIS issues with a small rough idle, but I have thoroughly enjoyed this M103. It has not once left me stranded in over 30k miles I have owned it for.

With 95k currently on the clock, hopefully I still have a lot of life left in this thing!

pawoSD · #56 07-23-2009, 07:30 PM

Well then.....too late now I suppose, as the valve seals are already underway/taken care of. We'll see if it makes a change, if its still just as bad, then I will look into pulling/reconditioning the head once I have my trans swapped in the SD.

#57 07-24-2009, 01:18 PM

Yes, I did mine about 140,000 miles ago and it's still going very strong.

A couple of items to pay particular attention to:

When laying the cam, get all caps and cap bolts started and finger tight, then turn them all a turn or two at a time so as to gradually pull down the cam so that you don't strip any bolt holes or break the cam.

Read up on angle torquing if you haven't done it before and do not get interrupted in the middle of the sequence. If you do, you can very easily get some over or under torqued. The sure fire way to avoid this is to mark them with a dab of paint so you know where you're at.

BTW, you might want to bench press a little extra weight for a few weeks leading up to torquing the head. It's a real work out. Unless you're in TOP shape, you will be huffing and puffing when you're done.

ps2cho · #58 07-24-2009, 02:16 PM

Quote:

Originally Posted by LarryBible

BTW, you might want to bench press a little extra weight for a few weeks leading up to torquing the head. It's a real work out. Unless you're in TOP shape, you will be huffing and puffing when you're done.

This! I had to get my dad to come and help me with this. He has a lot more weight on him than I. The 2nd 90 degree turn takes the life out of you. You better have a LONG wrench to get the leverage needed otherwise goodluck!!

pawoSD · #59 07-24-2009, 04:21 PM

New seals are in, old ones were rock hard. It runs beautifully. We'll see how it goes. My tech said that in his experience they respond well to new seals even with worn guides. Mine does have some worn guides....but that is a job for a couple years down the road at the earliest.

73Elsinore · #60 07-24-2009, 07:38 PM

When torquing the head bolts on my M104 I made a little chart in my notebook that had the bolt # and the three torquing steps (56 N-m, 90 deg, 90 deg). I wrote a number on the head next to the bolt with a Sharpie, then I made a check mark in the book as I completed each step for each bolt because all 14 bolts get tightened in sequence for each step. I used a 2' long snipe on the breakover for the last 90 deg step and it wasn't too bad. The hard part is watching the angle gauge while applying mustard to the snipe to make sure you don't over or undershoot the angle.

The manual is pretty specific on the cam install procedure and it says exactly what Larry recommends, telling you which bolts to tighten on what cam bearing cap.

I had my head rebuilt by Metric Motors in LA. It was $1200 OTD. They had to do a couple weld repairs for corrosion damage and all my exhaust valve springs were out of spec. I had one pitted exh valve that had to be replaced. I also sent them my cams to mike and they cleaned and reassembled the cam advancer mechanism on the intake cam.

Actually the most time-consuming part of this whole job has been the incessant cleaning. Clean the carbon off the piston domes. Chase the head bolt threads and clean them out. Clean all the oil mess off the motor and from under the car from the leaky head gasket. Clean all the crap out of the water jackets (you wouldn't believe what was in there). Clean all the oil out of the upper and lower intake manifold. Clean the throttle body. Clean clean clean. :-) Thanks! Pete