Diesel injector copper seal

[bkrum]

My 2010 Sprinter has exhaust leak on 3 injectors, so I have to replace the coppers seals.

Just wondering if the injector seats are flat or coned on the 3L V6 engine?

The new copper seals I bought are OEM, and seem to have a slightly coned shape, while the bottom of the injector it self is flat.

 

[Kajtek1]

Those are crush seals, so they can have weird shape before crushing.
Those engines are subjects to "black death" so don't save 20 cents on aftermarket seals and do your homework on torquing sequence.

 

[manwithgun]

Important to always use new factory stretch bolts whenever tension has been relieved and to follow torque guidelines. I’ll let someone else confirm whether washer orientation matters.

 

[sparkplug]

Well, I can't say for certain if it matters as I only installed mine one way round so I don't know if installing them the other way round would have worked or not....

However, based on a video I saw on YouTube and on looking at the washer and injector in my hands it made sense to me that there was a right and a wrong way round.

This is going to be harder to describe in words than a picture - but I don't have a picture so....

If you imagine the slight curve on the washer to be a 'bowl' then you would push the injector in through the top of the bowl so that it cups the bottom of the injector snugly. This is how I (successfully) installed mine.

If you do it the other way round you will see there is a gap between the injector and the washer. No idea if this works, but others have said it doesn't.

Another top tip from Dennis of Lindenengineering and Sprinter Forum fame is to apply the tiniest little dab of grease to the copper washer so that it just sticks to the injector. This makes inserting them really easy.

If you've had exhaust leak to the point of 'black death' then you will want to make sure all the threads for the stretch bolts have been properly cleaned out. I used one of the old bolts and ground a flat side on it to make a chaser or cleaner bolt. I was amazed at how much dirt came out and how many times I has to squirt brake cleaner in and chase the dirt out.

I also had some residue on the inside of the injector ports for which I bought a (cheap) special tool which had little caps to seal off where the injector nozzle goes through and a flexible soft metal brush to dislodge the dirt without allowing it to drop into the engine.

A little compressed air to blow it all out and all was well.

100% agree with using OEM washers and bolts here. They cost peanuts and aftermarket washers are not contoured to fit and are not necessarily the correct thickness. Aftermarket bolts don't always have the thread lock coating on them.

False economies.

Also the stretch bolts need to be torqued correctly (although there is some debate on what that should be).

There seems to be consensus on torquing them to 7Nm initially (which is not as tight as you might think). After that it seems that MB changed the recommendation from a further 90º turn to two rounds of 90º. So you would first do each injector to 7Nm then each injector 90º past that and then another 90º past that a second time rather than a single 180º turn

I did the 90º + 90º and it's been fine so far (4,000 miles)

Hope some of that is helpful.

 

[bkrum]

Interesting about the different opinion on torq specs! I suspect that the real problem with leaks is the 6mm bolt stretching too much, has anyone tried to install a 8mm? Should not be to hard to drill out and make new threads for it?

I also had to machine down the injector seat a bit to get an even surface, and used a flat tool. Maybe the MB tool is slightly coned, I don't know..

 

[bkrum]

Notice the small piece missing on the inner edge, this is no good, cause pressure will increase at that spot. Not sure how much I can grind down though, before the injector seats too deep for either the piston or losing the pressure of the holding clamp..

 

[irvingj]

In the FWIW department -- and please feel free to comment: My A&P recently explained to me how to orient the copper crush washers on my O-320's spark plugs. He explained that, as he was taught, the slightly curved surface of the washer should face the softer metal. That is to say, one side of the washer is flatter, with somewhat sharper edges -- that side should face the steel spark plug; the more rounded or slightly curved surface should face the aluminum engine head. This would also fit what sparkplug posted above.

Made sense to me; I had never had that explained before but noticed that stamped-out washers most always have a flatter side and a more curved side as a result of the stamping process. Any thoughts?

 

[bkrum]

Here's a new twist, talked to an aircraft engineer today, and he says that he would try applying some loctite (he's getting back to me with which one) on the copper seal to avoid new leaks. He has used it on oilfilters with great success where pressure and not enough torque to hold the seal was an issue.

 

[lindenengineering]

OK
Old age method works best!
Apply a nub of grease to the injector step.
Slip seal ring with dished side down.
Install injector and let heat carburize the grease sealing the injector seat .
Dennis

 

[bkrum]

OK
Old age method works best!
Apply a nub of grease to the injector step.
Slip seal ring with dished side down.
Install injector and let heat carburize the grease sealing the injector seat .
Dennis

Just the kind of info I was looking for!

Have you tried Loctite products or similar as well, or used grease every time?

 

[lindenengineering]

Just the kind of info I was looking for!

Have you tried Loctite products or similar as well, or used grease every time?

NEVER in 60 odd year have I used Loctite products on Injector installs.
The grease method was taught to me by old masters in the trade.
Dennis

 

[sparkplug]

Dennis' is the advice I listened to and it's worked perfectly for me

 

[Burkilimo]

Use “special ceramic grease” by Bilstein on the injector

 

[Kajtek1]

You need ceramic grease on injector upper body, to keep dirt away.
For copper washer all you need is clean assembly, it takes a plumber to use dope for connection sealing.

 

[nctrailseeker]

NEVER in 60 odd year have I used Loctite products on Injector installs.
The grease method was taught to me by old masters in the trade.
Dennis

Hmmm... But will it hurt anything to use Loctite or actually Permatex? ... Grey anti seize grease

God I hope not. I'll be pulling 2 different sets of injectors to wipe that stuff off and replace with something else. Tell me it's ok.

 

[lindenengineering]

Anti seize grease on the shank, nub of grease on the copper washer back face.
Refrain from loctite !
It has its places, & usages, but NOT holding down or sealing injectors.
Dennis

 

[nctrailseeker]

I checked, it's NOT Loctite. But it is Permatex ... Grey anti seize grease. So I think I'm good.

 

[bkrum]

Today it's assembly day, I have been away at work for a week. Think I will follow the advice with a nub of grease, also I will use Honda Accord 2.2 L washers, they are 2.4mm vs 1.52 MB i believe.

 

[sleeper bird]

seems to me that being you are using thicker seals,wouldnt that throw all of the torque values off?

 

[nctrailseeker]

seems to me that being you are using thicker seals,wouldnt that throw all of the torque values off?

Right. I think that’s a big mistake. If MB thought it was a good idea, they would have used 2.4 mm in the first place.
Let us know how that works out for ya.
Let us know how many hold down bolts snap right before reaching proper torque.