Midway through replacing glow plugs, compression test? cleaning intake? Advise please - PeachParts Mercedes-Benz Forum

BoneSinSC · #1 09-19-2012, 03:44 PM

Hey all.

First off this is on a 98 e300. I'm happy to report that I managed to get all 6 plugs out without breaking anything. After having read so many nightmare threads about this procedure on here and other Mercedes forums, I can not tell you how relieved (and happy) I am! I'm going to go ream the holes shortly but was wondering if anyone could provide some advise on performing a compression test. I know the basic procedure (and yes I've googled

) but wanted to know about disabling the fuel source, which I assume is done by unplugging? fuel shut off solenoid? can anyone shed some light on that. Also, I'm doing this job alone so would just jumpering the starter work as a means to get the engine to turn?

Other question has to do with air intake. Well, not the air intake but the air intake on the head. Those holes are filthy! Obviously have to be careful in cleaning them so does anyone have a suggestion of how do do so? The actual air intake I have sitting with some biodiesel in it so hopefully that will take care of that part (which was also filthy). Would a filthy intake reduce engine mileage? The reason I ask is that my car gets lousy gas mileage and has pretty much since I bought it last April.

thanks for any help you can provide.
back to work
Tony

TMAllison · #2 09-19-2012, 04:27 PM

You can pull the electrical connection to the Shut off Valve on the side of the IP to keep it from spitting fuel. You'll have to clear a code later probably.

B100 didn't do too much to the inside of my IM when I tried it. Took lots of scrubbing. Steam cleaning or hot dipping would work best. Some folks have sprayed it down with Gunk or Brake cleaner and then gone to the local self serve car wash and sprayed them. Might get arrested doing that in Santa Cruz....

What kind of MPG's are you getting and what is the ratio of City versus Highway driving that you do? Are you burning D2, Bio, home brew bio or veggie?

Diesel911 · #3 09-19-2012, 04:54 PM

I they were mine I would put a Never-seeze type compound on the threads of the Glow Plug before I install them; or that special Beru Glow Plug Grease if you can find it.

More than one person has said they used Oven Cleaner on their Manifold others Engine Cleaner.

BoneSinSC · #4 09-19-2012, 05:47 PM

@TMAllison Bummer that BioD didn't seem to work for you. I'm about to try it out and only using it because "Lightman"s excellent write up on glow plug removal mentions that what he used with great success. If that doesn't work, I think I'll try something like brake cleaner, foaming engine cleaner or even something a bit more caustic. I guess oven cleaner does make sense as well.
I'll report back with what worked when I'm done. As for my gas mileage, I seem to be getting less than 20 mpg in the city and even on the highway, about 27 or so. This is mainly with B100, but I had similar results with diesel. I'll probably run a can of diesel purge through there as I'm due for an oil change and see if that helps. I half suspect that a dirty injector is part of the cause of my glow plugs failing - two of them failed in the last month or so.

@Diesel911 I'll definitely add some anti seize (nickel based) to the threads AND body. I'm going to post some pics of my glow plugs when I'm done mainly to show that the corrosion on them is on the body of the plug and that whatever binding I experienced when trying to remove them is caused by the dissimilar metals of head and glow plug and nothing to do with the threads. Stay tuned.

cheers
Tony

TMAllison · #5 09-19-2012, 07:49 PM

I burned a fair amount of B100 for a while. It made my turbo come on much more that it did when D2 was in the tank. I usually got 5-10% less mpg on B100. If work hadnt have footed the fuel bill I wouldn't have used it because it certainly wasnt cost effective.

The 99' E300 used to get 30-32mpg on my comute from Walnut Creek to SJ burning D2. That was usually 80miles at 70mph and 30 miles at 10-20mph.

After I started working from home and only drove 2 miles to school or soccer practice a few time a week my mpg's dropped to the low 20's.

The 09 E320 is getting about 23-24mpg around town and about 38 on the highway.

Diesel911 · #6 09-19-2012, 11:15 PM

Biodiesl is like Gasohol, there is less available Energy in it when burned.

From the Below site; "Lower fuel economy and power (10% lower for B100, 2% for B20)"
There is no mention of a Turbocharger use in the comment.
Biodiesel

BoneSinSC · #7 09-20-2012, 04:24 AM

even though I think it could be quite useful with my low mpg issue. I had no choice as the kit I have has a right angle 12mm adapter for Mercedes and with the angle of the glow plug holes, you simply can't thread it because it hits the head. Oddly enough, other kits I have seen seem to have the same type of adapter for a Mercedes so what gives? Anyone else have this problem?

As for the running on biodiesel. B100 is supposed to have about a 5% reduction in power when compared to dinodiesel but that's still not enough to explain my lack of miles per gallon. I'll probably try to tackle that issue after doing a good bit of searching and reading on here.

Thanks for your input though.
Tony

TMAllison · #8 09-20-2012, 10:49 AM

Whats your mileage on the car?

Ever rebalanced the inj's? Checked chain stretch?

BoneSinSC · #9 09-20-2012, 03:08 PM

I think I just passed 120K on the odometer. It runs great on the highway and doesn't seem to have any engine issues. In other words, if I didn't calculate my MPG, I wouldn't think there was anything going on with it.

cheers
Tony

GregMN · #10 09-20-2012, 03:50 PM

Quote:

Originally Posted by BoneSinSC

I'll definitely add some anti seize (nickel based) to the threads AND body.

Use a reamer to clean the carbon out of the holes before you install the glow plugs. That is almost as important as the use of anti-seize.

TMAllison · #11 09-20-2012, 07:58 PM

Quote:

Originally Posted by BoneSinSC

I think I just passed 120K on the odometer. It runs great on the highway and doesn't seem to have any engine issues. In other words, if I didn't calculate my MPG, I wouldn't think there was anything going on with it.

cheers
Tony

Yours is still a pup. After making sure you have 225/55 16R tires and the brakes arent dragging, I'd do things like making certain the air filters are clean and that it isn't dripping (wasting) fuel although the latter would usually show up as hard starts.

Its possible the inj's need to be balanced although mine stayed in for 311k and I never pulled them.

Your mpg's are probably a result of a heavy foot and lots of city driving.

BoneSinSC · #12 09-24-2012, 02:21 PM

and a pic or two below.

Thanks to those who replied. The glow plug gods were kind as I didn't have any problem removing them. I think this was in part to me having sprayed them (only glow plugs 1-3 actually) liberally with Kano AeroKroil for several days BEFORE I started the job. Though glow plugs 4-6 also came out without too much trouble as well. I know everyone seems to have a favorite "penetrant" but this is mine. On the 3 plugs I did spray, the shaft of the plugs were wet with the penetrant, so I know this stuff was actually getting into the glow plug hole
and working it's magic.

I'm posting photos of my glow plugs here so that people can see that it's actually the shaft and not the threads that are the problem. You can clearly see that the shaft had started to bond with the head because of the whole dissimilar metal thing. I think these plugs have been in the car for 10 yrs or so as they are marked with "2001" on them. I smeared some anti-seize liberally on the shaft and threads before installing. I used the nickel based as I think copper based would only contribute to the problem with aluminum head.

I did ream out the glow plugs holes. There was plenty of carbon build up in there as the reamer had to be gently tapped into the hole because it was so clogged. I think if you are going to take the time to do this job yourself, definitely ream the holes.

Final thoughts: nothing too complicated on this job. It's pretty straightforward if you go slooowwww and are lucky enough to get your plugs out without breaking any of them. What took me the longest was cleaning up the air intake. Mine was not only coated with soot but lots of oil which made it quite hard to clean. I used a combo of soaking in BioD overnight and then several cycles of citrus degreaser, hot water and even a bit of boraxo. In the end I got it pretty clean but lots of dirty fluids to dispose of now. I'll probably research the whole EGR thing because I'm not sure I should be getting that much oily residue in there but then again, it's quite likely this thing hasn't EVER been cleaned.

cheers,
-Tony

BoneSinSC · #13 09-24-2012, 03:19 PM

Notice that the new Bosch plugs don't seem to be coated with same material.

http://tinyurl.com/8lue4xo

cheers
Tony

Diesel911 · #14 09-24-2012, 04:57 PM

Quote:

Originally Posted by BoneSinSC

and a pic or two below.

Thanks to those who replied. The glow plug gods were kind as I didn't have any problem removing them. I think this was in part to me having sprayed them (only glow plugs 1-3 actually) liberally with Kano AeroKroil for several days BEFORE I started the job. Though glow plugs 4-6 also came out without too much trouble as well. I know everyone seems to have a favorite "penetrant" but this is mine. On the 3 plugs I did spray, the shaft of the plugs were wet with the penetrant, so I know this stuff was actually getting into the glow plug hole
and working it's magic.

I'm posting photos of my glow plugs here so that people can see that it's actually the shaft and not the threads that are the problem. You can clearly see that the shaft had started to bond with the head because of the whole dissimilar metal thing. I think these plugs have been in the car for 10 yrs or so as they are marked with "2001" on them. I smeared some anti-seize liberally on the shaft and threads before installing. I used the nickel based as I think copper based would only contribute to the problem with aluminum head.

I did ream out the glow plugs holes. There was plenty of carbon build up in there as the reamer had to be gently tapped into the hole because it was so clogged. I think if you are going to take the time to do this job yourself, definitely ream the holes.

Final thoughts: nothing too complicated on this job. It's pretty straightforward if you go slooowwww and are lucky enough to get your plugs out without breaking any of them. What took me the longest was cleaning up the air intake. Mine was not only coated with soot but lots of oil which made it quite hard to clean. I used a combo of soaking in BioD overnight and then several cycles of citrus degreaser, hot water and even a bit of boraxo. In the end I got it pretty clean but lots of dirty fluids to dispose of now. I'll probably research the whole EGR thing because I'm not sure I should be getting that much oily residue in there but then again, it's quite likely this thing hasn't EVER been cleaned.

cheers,
-Tony

It can be any of or all three: Heater Element trapped by Carbon Build up, Carbon got by shoulder sea area and carboned up body of Glow Plug and corroded threads.