Fuel Injector heat shields won't come out - PeachParts Mercedes-Benz Forum

RML · #1 12-22-2014, 08:27 PM

I have replaced the nozzles in my fuel injectors (84 300D) with new Monarks and am ready to put the cleaned and tested injectors back in, but I cannot get the heat shields out of the two cylinders closest to the firewall. The others came out with no resistance at all. I have sprayed WD40 in and let them sit but they are not budging. Not sure what to do next. Easy out?

Onetoomany · #2 12-22-2014, 08:30 PM

Quote:

Originally Posted by RML

I have replaced the nozzles in my fuel injectors (84 300D) with new Monarks and am ready to put the cleaned and tested injectors back in, but I cannot get the heat shields out of the two cylinders closest to the firewall. The others came out with no resistance at all. I have sprayed WD40 in and let them sit but they are not budging. Not sure what to do next. Easy out?

Use some brake or carb cleaner on them, then let it evaporate then use a bit of PB blaster.

If you have a torch that will make a bit of heat in there, use it between the cleaner and the PB blaster.

Buggering up a prechamber will be a royal headache. Solvable, but $150+ and hours out of your day.

TnBob · #3 12-22-2014, 08:31 PM

Id spray some Kroil in there, let it sit a bit and then use a right angle pik to help them out

greazzer · #4 12-22-2014, 08:51 PM

Although folks have used disparaging comments on this method, but it has always worked. AND, to date, I still have not heard one explanation on how this could be harmful to one's engine or life.

Crank the engine. They should pop right out.

sixto · #5 12-22-2014, 08:59 PM

If soaking and picking doesn't work:

1) Thread a long lag screw into the seal to pull it out. Make sure there's a seal in place so you don't damage the prechamber!

2) Set a heavy rag over the prechamber opening and crank the engine. Compression should blow out the seals. Hold down the IP stop lever so you don't spray fuel.

Sixto
MB-less

funola · #6 12-22-2014, 10:32 PM

And make sure you don't get hit in the face lol. A safer method is use a 1/4 or so diameter flat face punch and hammer. A few taps on the perimeter of the heat shield to break the carbon bond. Always worked for me.

RML · #7 12-22-2014, 11:34 PM

Well, I went back and was going to try my easy out, but it was too small. I shot some penetrating oil in and then tried the right angle pick again. Nothing. So then I tried picking it out with the little tool they give you at the hardware store to open the paint can when you buy paint. I think I bent number four just enough to dis-form it and it popped out. It was pretty crusty with carbon. Number five did not want to budge yet. I was trying with the paint can opener but the tool was bending. So then I got a slotted screwdriver and tapped it down into the heat shield so it got lodged and then turned a bit and it popped loose.

Thanks for the suggestions. I got the injectors back in, torqued down, the braided hose on and the lines to the injector pump hooked up. Tomorrow I will bleed the lines and start her up. After some sputtering and coughing, I am hoping to have a much smoother running engine. I did a diesel purge before I took the old injectors out. The primary filter was pretty gunked up and when I changed the spin-on secondary filter this evening, a lot of crap came out when I turned it over and emptied out the fuel. I had a problem with algae in the tank about a year ago and I used a biocide. I think this was the remains from the dead algae.

Diesel911 · #8 12-22-2014, 11:53 PM

For someone else reading this.
If you are installing New Injector Nozzles use the Heat Shields for 1980s VW Rabbits. They have a smaller 5mm hole and it is easier to hook something inside of them to yank them then it is on the Heat Shields with the 10mm Hole when it comes time to remove them.
The 5mm holes also expose less of the Injector Nozzle to heat.

The Heat Shields I took out of My Engine and the ones I ordered to replace them back in 2007 had the 5mm hole. No one has ever explained why vendor are selling the ones with the 10mm holes for mercedes.

Also note that the old VW Rabbits and My Volvo Diesel can use the same Injector Bodies so I further don't know why the Heat Shields between Mercedes and them are different now then in the past.

Also there is a bunch of methods on Heat Shield removal in the DIY section:
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Shortsguy1 · #9 12-23-2014, 12:08 AM

Quote:

Originally Posted by Diesel911

For someone else reading this.
If you are installing New Injector Nozzles use the Heat Shields for 1980s VW Rabbits. They have a smaller 5mm hole and it is easier to hook something inside of them to yank them then it is on the Heat Shields with the 10mm Hole when it comes time to remove them.
The 5mm holes also expose less of the Injector Nozzle to heat.

I believe heat shields on the very early MB diesels had a smaller hole than the one specified for the OM61X engines today. So at some point, MB engineers decided to require a larger hole in the heat shields. I have thought long and hard about this, and I suspect it is because of carbon build up. If the hole is smaller, you are more likely to get carbon buildup interfering with the injector spray. So yes, a smaller hole shield will be easier to remove from the prechamber, but it could affect spray patterns. If in doubt, I tend to trust the engineers at MB to design or specify the best part for their engines.

winmutt · #10 12-23-2014, 12:29 AM

Sixto and greazzer were on it. I failed to do the rag trick and it ended up putting a dent into the hood. Just think about the compression pressure it takes to do launch it 3ft and put that kind of dent in.

Lucas · #11 12-23-2014, 01:40 AM

Quote:

Originally Posted by winmutt

Sixto and greazzer were on it. I failed to do the rag trick and it ended up putting a dent into the hood. Just think about the compression pressure it takes to do launch it 3ft and put that kind of dent in.

Lol. That is quite the trick. I did that to get remaining MMO out of the cylinders. Spent a little time cleaning the ceiling in the garage. Didn't think that one through.

Surprised no one said magnet.

Edit: ok now understanding how stuck they get. I got lucky I guess. One motor didn't have any. Spent forever triple checking I wasn't missing something.

winmutt · #12 12-23-2014, 02:18 AM

Quote:

Originally Posted by Lucas

Lol. That is quite the trick. I did that to get remaining MMO out of the cylinders. Spent a little time cleaning the ceiling in the garage. Didn't think that one through.

Surprised no one said magnet.

Pretty sure I've applied atleast 10lb+ on those buggers before.

Stretch · #13 12-23-2014, 02:26 AM

Quote:

Originally Posted by RML

... So then I got a slotted screwdriver and tapped it down into the heat shield so it got lodged and then turned a bit and it popped loose.

...

That's how I did it when faced with the same trouble

vstech · #14 12-23-2014, 08:55 AM

For me, there was TONS of carbon all over the shield and the nozzle area. Soaking in PB blaster and CLEANING all the carbon out of the area solved the problem. It's most important to clean it all so there is a good seal on the new shields!!!

fahrvergnugen · #15 12-23-2014, 09:15 AM

Quote:

Originally Posted by winmutt

Sixto and greazzer were on it. I failed to do the rag trick and it ended up putting a dent into the hood. Just think about the compression pressure it takes to do launch it 3ft and put that kind of dent in.

I wondered how the PO got dents in the top of the hood; now I know. I think there are at least 4.

I'd be curious if there were any downsides to using the VW heat shields.