Injectors on D-Jets - Question about seals

[Graham]

I am cleaning and testing a set of injectors I bought from a forum member. They are blue Bosch 0280150036. After cleaning, I want to replace the seals.

- The large o-ring that has a circlip under it - Do I have to destroy the seal to remove it?

- Do the new large o-rings need heating or lubing to get them to slide on?

- The bottom has the top-hat shaped seal. But, there appears to be a plastic seal that fits over the end of the injector. This is broken on some of the injectors. Is this sleeve part of injector or part of top-hat seal? I don't see the sleeve listed as as separate part.

[Gurunutkins]

if you mean the very end of the injector covering the working bits its called a pintle cap. I buy mine in bulk bags and they generally sell for between 1 or 2 dollars each from injector cleaning shops like dr injector etc.

generally with the big rubber ring that you use to seat the injector, sits under the metal plate that fastens the injector to the manifold and then has the circlip under the o ring so it cannot slip down, just pull off the circlip and it should slide off. might need a bit of lubrication but its just pushed on

cheers
barri

[Tomguy]

The large "Seal" isn't a seal - it is just a gasket that helps retain the injector in place. The only part that really seals anything is the one you showed the picture of. The large circlip comes off if you have the proper removal tool.

If ANY of your pintle caps are worn or cracked, replace them! They are needed for proper atomization of the fuel.

[Graham]

Originally Posted by Gurunutkins

if you mean the very end of the injector covering the working bits its called a pintle cap. I buy mine in bulk bags and they generally sell for between 1 or 2 dollars each from injector cleaning shops like dr injector etc.

generally with the big rubber ring that you use to seat the injector, sits under the metal plate that fastens the injector to the manifold and then has the circlip under the o ring so it cannot slip down, just pull off the circlip and it should slide off. might need a bit of lubrication but its just pushed on

cheers
barri

Thanks barri/tomguy,

I wasn't sure if the "pintle cap" was part of the bottom seal or not. So I guess I need to order the caps separately. Not in on-line catalogues, so I guess I go to Dr.Injector or ???? - Would NAPA have that sort of thing?

The pintle caps are on very tight. What is best way to get them off if I want to replace them? Or should I just leave the good ones on?

The upper O-rings are tight - I think the heat has got to them.

One other thing. There is a filter on the inlet. It's easy enough to get them out. Are those available too, or should I just try and clean them?

[Gurunutkins]

Hi Graham
I just nick the top of the pintle cap with a razor and then "peel" them off, its really easy they are very thin (I have a couple I am cleaning right now so can send you pictures with the pintle caps removed if you want) I would do all of them, they are cheap from the injector stores and they are good protection for the end of the solenoid pin. If you cannot get them cheaply let me know and I will find you some down here.

To install I have a special jig but all you really need is a piece of hardwood with a small hole in it and then just put the cap in the hole and push the injector into it. Hardwood or plastic is best as softwood tends to shed fibre and you dont want that.

the big rubber o rings can be bought at NAPA or similar and are cheap, but buy the top hat injector seals from benz its not worth messing about with cheap copies of those

I always pull the filters and unless they are solid just stick them in your ultrasonic cleaner with professional injector cleaner, if you dont have any then use something like 50% sea foam 25% mineral thinners and 25% STP total injector cleaner, techron or similar injector cleaner concentrate.

hope thats some help
cheers
barri

[Gurunutkins]

sorry by the top of the pintle cap I mean the thick end near the body of the injector not the end furthest away from the injector. I just ran up and took some pics on one. just make a small nick at the top, score down to near the end then peel it open and off with your fingers. dont cut across the hole in the end or you may damage the solenoid pin end and it will mess up your atomisation. I am down to my last 8 caps which I am saving for these 8 injectors but I can get more if you cannot find any
cheers
Barri

[Graham]

Originally Posted by Gurunutkins

Hi Graham
I just nick the top of the pintle cap with a razor and then "peel" them off, its really easy they are very thin (I have a couple I am cleaning right now so can send you pictures with the pintle caps removed if you want) I would do all of them, they are cheap from the injector stores and they are good protection for the end of the solenoid pin. If you cannot get them cheaply let me know and I will find you some down here.

To install I have a special jig but all you really need is a piece of hardwood with a small hole in it and then just put the cap in the hole and push the injector into it. Hardwood or plastic is best as softwood tends to shed fibre and you dont want that.

the big rubber o rings can be bought at NAPA or similar and are cheap, but buy the top hat injector seals from benz its not worth messing about with cheap copies of those

I always pull the filters and unless they are solid just stick them in your ultrasonic cleaner with professional injector cleaner, if you dont have any then use something like 50% sea foam 25% mineral thinners and 25% STP total injector cleaner, techron or similar injector cleaner concentrate.

hope thats some help
cheers
barri

I might take you up on finding some pintle caps - But I will look around and see if I can find them here or on-line. Only source I have found so far is Mr Injector and his prices are not exactly cheap. I have 16 injectors that I want to do.

In the pictures you posted the injectors have a single O-ring - Is that a different style? Mine have the hat shaped seal I posted a picture of earlier.

One other question! Do you know if the yellow injectors as used on the Euro 3.5L SLs would physically fit on the 4.5L engine? I was thinking about raising the rail pressure a bit more so as to totally eliminate the vaporization that can cause hot start problems in fall and thought that maybe I could go to a lower capacity injector to compensate.

[Gurunutkins]

to the best of my knowledge (which is sometimes very dodgy) all of the hose fed bosch injectors will physically fit our cars. They wont necessarily all run them well but they will fit. The ones in the picture above have green o ring seals fitted for the California smog regulations, they didn't like the hat type seals and asked for the green o ring. I have changed mine over to the hat seals as I think they are better but its 6 of one and half a dozen of the other. Let me know how you go on the pintle caps
cheers
barri

[DJet Tragic]

Originally Posted by Graham

One other question! Do you know if the yellow injectors as used on the Euro 3.5L SLs would physically fit on the 4.5L engine? I was thinking about raising the rail pressure a bit more so as to totally eliminate the vaporization that can cause hot start problems in fall and thought that maybe I could go to a lower capacity injector to compensate.

I grabbed a set of Yellow injectors from a 350 wreck a few months ago.
Do these Yellow injectors have a significantly different capacity to the Blue?

Is there a safety issue with the Yellow injectors? I have a vague recollection of a warning that they might leak - or something!

Bari - great information & pix; as usual.

Peter in Melbourne

[Jengasan]

I think the yellow injectors leak thing is a bit of a myth, certainly mine never have and 6 of them are original as far as we can tell...not bad for 37 years. The difference between the yellow and blue is their fuel flow, blues are higher as far as I know but i can't remember the actual numbers off hand. Suffice to say that the blues are way over spec'd for the engine capacity (4.5l) as i'm sure I have read that they have a much higher output than standard 5 litre mustang items. This is maybe a factor of when the ecu was designed etc etc. I think Gurunutkins may have data on this from his megasquirting adventure but I may be wrong (sorry GN). Anyway...yellows are fine, have fun.

J

[Gurunutkins]

Hi Peter, hope the project progresses well. I have to agree with Jengasan, probably pure myth. I have had injectors leak on me but only one leaked from the body around the electrical connector, probably been dropped at some time and it was an 036 from a 450. I have had a few leak from the pipe though (of all sorts not just yellow). One thing I always do is to cut off the bottom hose collar and replace the hose. always use high pressure hose (160psi) to replace it not the cheap 50psi fuel line hose and always use compression clamps not jubilee (water pipe) clamps to fix the new hose on. depending on your source for info they are listed as being 307 ml per hour to 370ml per hour if you have a bosch number I can look it up in my bosch book. the number is along the side of the electrical connector and old fart eyes like mine need a magnifying glass.
cheers
barri

[Graham]

This site has a good summary of injectors:

http://www.sdsefi.com/injectors.htm

The table I found says 485 cc/min for blue (0280150036) and 338cc/min for the yellow (0280150034). But as barri said, different sources give different numbers. I got my numbers here:

http://www.injectorcleaning.co.uk/flow.htm
(this site also has interesting pictures on desired flow patterns.)

At 30psig, flows would be 402 and 280 cc/min.

If the yellow injectors were installed in a stock 4.5L M117 engine and pressure raised to say 34 psig, then flow would be 298 cc/min. If I adjusted the MPS to give the proper CO in exhaust (~2%), would the stock ECU compensate for the slightly lower rated injectors?

I don't have a way to measure CO . I would either have to buy one of those British GasTesters for several hundred $$ or find a shop to do it for me - Not likely. If I wanted to do it from A/F ratio, I would need to install an O2 sensor (or 2) like barri did on one of his cars. But, are those bar graphs accurate enough to really set the mixture? Any suggestion for a budget way of measuring CO or AFR?

[JeffreyNMemphis]

Glad to see this topic today... I need to change two injectors on my 73' 280SEL 4.5. I bought a set of seals to do the whole thing. I am doing my valve cover gaskets tomorrow and planned on doing the injectors and seals while the hood is open.

[Gurunutkins]

Hi Jeffrey, a good set of jobs to do! my only comment is if you are changing seals on a non california car (one with the top hat seals) have a pair of long tweezers at hand. If the seals are really old and wasted the top part of the top hat seal tends to come off stuck to the injector and the smaller part that goes into the holder tends to stick in the holder and you need some long nosed tweezers to pick it out so it doesn't fall into the manifold I doubt it would do much damage as people loose pintle caps all the time but its just not worth the heart ache to drop it in there when you could be ready with forceps.

Hi Graham, I know what you mean about the sites here are 2 more the first http://users.erols.com/srweiss/tableifc.htm#BOSCH is pretty good but I know the figures on the 280 150 036 are wrong but his 015, 024 and 026 are probably right (they agree with my book) and are used on various rest of the world 350's. this site http://www.witchhunter.com/injectordata1.php4 agrees with my book on the 036 and not the others (just find the injector number in the hose end section and click on it for details).

If you run your smaller injectors at a slightly higher pressure you will probably run more economically at low speeds and below 3000 rpm there is little chance of damage but if you get it wrong then at WOT you could overheat your engine badly and in the worst case you can melt a piston top. The o2 sensor running an AFR gauge is actually quite accurate on getting the mix right, it trails the engine by 4 or 5 seconds but what you will see is that as you accelerate the bars drop right down to lean even with a good set up and then climbs to over rich on deceleration until the ecu responds. this is mediated by the TPS which on acceleration becomes the main sensor and will defeat the MAP for the first few seconds until the MAP realizes that the vacuum is dropping to zero and takes over for the TPS and really pours in the gas.

So the afr is great for when you are actually driving at an AFR of 14.7:1 but on either side of that its either showing a rapid drop to lean or a fast rise to over rich so not much help to you in tuning unless you can hold the engine at a fairly steady state.

however after all of the above I would feel relatively happy running yellow injectors at 34 to 35 psi in a 450sl. I would stick in an afr gauge and start off with very staid driving then start pushing the accelerator and easing off again and watching how fast the afr gauge came back to mid range on deceleration. if it took more than 2 or 3 seconds (on top of the 4-5 second lag so 6 to 9 seconds overall) try pumping up the pressure by 2 psi. you should reach a point where you get some quite economical cruising with acceptable acceleration. I would not go for WOT type acceleration however. as you may burn something. Also its just guess work on my part but I'd be comfortable trying it

cheers
barri

[Jengasan]

Graham - re the top hat seals. I did these on my car and I'm fairly convinced they were the originals considering their condition. I've noticed in the post above that the guys are saying have tweezers or forceps handy to grab the bits - good advice but in my experience the seals had got so hard that they literally disintegrated when we removed the injectors. We found the best way to deal with this was get a vacuum cleaner and fashion a smaller diameter nozzle (we taped some 10mm central heating pipe on the end of the standard vacuum hose via a plastic cone - thus creating 'the probulator'), we then used this to suck all the debris out while pulling the injectors. We got a lot of dry rubber and one pintle cap in the vacuum bag. For good measure we even stuck the 'probulator' down the injector ports carefully and let it suck away just in case, I'm personally convinved that we did remove some debris from the heads using this method. Suffice to say that the car has done at least 3k miles since the injectors were done and there has been no sign of any debris damage (not that it would be that easy to tell I suppose). Basically if you're going to do the top hat seals when the heads are on, especially if they are very old, I'd recommend using every trick you can think of to catch the bits that WILL fall off when you pull the injectors. Rant over...best of luck mate

J