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Quick question on Injectors. Not really used the car for last 12 months, and been doing lots of maintenance recently on rockers and shaft etc. Over the last weeks have discovered problems with 3 injectors and replaced with spares.

Examining the faulty injectors, they all "rattle" when shaken end to end. When you pull out the front spike it has spring pressure and then retracts. However the front dome (which houses the springed spike)seems to move in and out with no resistance?

Any ideas whats gone wrong, has an O ring failed and can I fix this myself or do I have to have it refurbished professionally

Cheers, Colin.

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Yes it's an o ring inside that holds it all tight. Quite easy to replace, it's getting hold of the right size that might be the issue. 

I did purchase some a while back but I have no idea where from our the sizes now. Maybe do a search on injector o ring and it might come up. 

Also it has to be the correct grade to withstand the modern fuel. 

Gareth

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1 hour ago, Mk2 Chopper said:

Yes it's an o ring inside that holds it all tight. Quite easy to replace, it's getting hold of the right size that might be the issue. 

I did purchase some a while back but I have no idea where from our the sizes now. Maybe do a search on injector o ring and it might come up. 

Also it has to be the correct grade to withstand the modern fuel. 

Gareth

Thanks Gareth you have confirmed my thoughts.

I have found a some o rings labelled in a bag amongst all my spares labelled......................"£ 3.00, from Chris Witor proper injector O rings 6 off - Viton" which I must have brought way back and forgotten about. Guess as long as you dont adjust the internal allen key spring that sets the pressure,replacing the front o ring is worth a try?

Cheers, Colin.

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Sorry one other question whilst I am here regarding the white injector bush that fits into the throttle body. The o ring is not central on the bush, so which way round does it fit, ie with the o ring closer to the bottom or closer to the top?

It also seems that the injector is a loose fit into the bush if fitted with the o ring at the top, so looks like it is tapered?

Thanks Colin.

 

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1 hour ago, c.hydes said:

Thanks Gareth you have confirmed my thoughts.

I have found a some o rings labelled in a bag amongst all my spares labelled......................"£ 3.00, from Chris Witor proper injector O rings 6 off - Viton" which I must have brought way back and forgotten about. Guess as long as you dont adjust the internal allen key spring that sets the pressure,replacing the front o ring is worth a try?

Cheers, Colin.

Yes it can't do any harm, as you say don't adjust the spring rate. The new o ring might need to swell with fuel or you may find its already a tight fit. It should then prevent fuel draining through the body. 

32 minutes ago, c.hydes said:

Sorry one other question whilst I am here regarding the white injector bush that fits into the throttle body. The o ring is not central on the bush, so which way round does it fit, ie with the o ring closer to the bottom or closer to the top?

It also seems that the injector is a loose fit into the bush if fitted with the o ring at the top, so looks like it is tapered?

Thanks Colin.

 

I can't actually remember, but I'd put it the tightest way so you don't create a vacuum leak. 

Gareth

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5 hours ago, Mk2 Chopper said:

Yes it can't do any harm, as you say don't adjust the spring rate. The new o ring might need to swell with fuel or you may find its already a tight fit. It should then prevent fuel draining through the body. 

I can't actually remember, but I'd put it the tightest way so you don't create a vacuum leak. 

Gareth

I have spoken to the experts. The "push in" type injector insulating bush has two groves,  one is V shape and one square shape. The o ring goes in the square shaped groove. 

Looking at the ends of the bush, one end is flat shaped and the other end has a ridge with "castlelated ridges" nearest the o ring seal. The flat end goes to the bottom of throttle body. Once fitted the o ring is then at the front and the injector inserted. Apparently this gives the best air seal.

So there you go, ............................so much to learn but so little time !!

Colin.

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Hi Colin

I have dismantled the injectors quite a few times and replacing the o rings is quite easy after you have done it few times.  Be careful when taking off the metal retaining ring & do it in a plasic bag if your worried.  I use a piece of wood to press out the inside ,shaped like a round pencil. Use a bit of vasaline when putting on the o ring and re assembling as there is a ridge in the bore of the injector, to avoid damage. I  then use a tyre pump with a inflatable bed adapter which is coned shaped to check that injector is popping off of at about 50/55 psi. Easy to adjust.

Good luck  Roger

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I like the pump trick, but I am thinking as long as all injectors are working do they need any adjustment? It won't affect the spray pattern...or does it? 

Gareth

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11 hours ago, Rogcastle said:

Hi Colin

I have dismantled the injectors quite a few times and replacing the o rings is quite easy after you have done it few times.  Be careful when taking off the metal retaining ring & do it in a plasic bag if your worried.  I use a piece of wood to press out the inside ,shaped like a round pencil. Use a bit of vasaline when putting on the o ring and re assembling as there is a ridge in the bore of the injector, to avoid damage. I  then use a tyre pump with a inflatable bed adapter which is coned shaped to check that injector is popping off of at about 50/55 psi. Easy to adjust.

Good luck  Roger

Hi Roger, I have tried to replace the o rings on two injectors now. Getting the circlip off is quite easy as well as getting it back on again once you have the technique sorted. Once removed the inside valve assemblies both slid out when turned upside, so that was easy too. On both valves the small o rings were flat in their groove, getting them out was easy as was replacing the new rings using some "3 in 1" oil. However, even with oil on the inside bore they would only push in about 15 mm. They then got very tight, and the problem is there is nothing to push on at the rear without possibly damaging/moving the valve at the back. It looks delicate and didn`t want to risk breaking something.

So whats the secret of pushing them back in?

Cheers, Colin

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12 hours ago, Mk2 Chopper said:

I like the pump trick, but I am thinking as long as all injectors are working do they need any adjustment? It won't affect the spray pattern...or does it? 

Gareth

I also use the pump method, have done for years and use a high pressure cycle pump that can pump up to 150psi and has a non calibrated gauge which gives an indication of the blow off pressure and a non return valve. I turned up a special adaptor to screw directly on to the injector and to fit the pump adaptor. With this system you can check how good an injector holds air does if it does not, it will not spray properly and leak? Any new re- con injectors I check before installing! Any that fail this test get sent back! It is also a very good indicator on used injectors. You can also place the injector in water to see exactly where it is leaking, it is not always the O ring?

Bruce.

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3 hours ago, c.hydes said:

So whats the secret of pushing them back in?

Can't you use an Allen key in the adjuster and push it in firmly? 

Gareth

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Hi Colin

They will go in if your sure you  have the right size O rings.  Make sure the rings are well lubricated and inside the tube, then do as Gareth suggests. :D

Roger

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33 minutes ago, Rogcastle said:

Hi Colin

They will go in if your sure you  have the right size O rings.  Make sure the rings are well lubricated and inside the tube, then do as Gareth suggests. :D

Roger

Roger/Gareth, the o rings were brought from Chris Witor (ID = 4.5 x OD = 8.0 x 1.8 mm Viton) and confirmed by a QA engineer on a shadow graph before I retired. I can only assume that they are correct unless others can say otherwise. I did use plenty of oil, and indeed try pushing hard on the allen key. However I don`t have the facilities that Bruce has developed for setting the pressure, and didn`t want to risk moving the allen key and hence changing the calibration. 

It would be good to sort this out considering how many people have problems, but more importantly how costly it is to have them refurbished (about £30 a pop) !! 

Can anyone confirm the o ring dimensions are correct please?

Colin.   

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Colin,

I made a note in my wsm. Think this info came from this forum:

Viton Grade B (not A), 75 Sh hardness.

OD: 5/16” (7,94 mm)

ID: 3/16” (4,76 mm)

Thickness: 1/16” (1,59 mm)
 

On these small diameters a tenth of a mm can be a lot, especially on thickness.

 As said, liberally lubricate.

I think Neil Ferguson charges less, he did mine, Excellent quality and this was one of those happy experiences during my TR restoration.

Cheers,

Waldi

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8 minutes ago, Waldi said:

Colin,

I made a note in my wsm. Think this info came from this forum:

Viton Grade B (not A), 75 Sh hardness.

OD: 5/16” (7,94 mm)

ID: 3/16” (4,76 mm)

Thickness: 1/16” (1,59 mm)
 

On these small diameters a tenth of a mm can be a lot, especially on thickness.

 As said, liberally lubricate.

I think Neil Ferguson charges less, he did mine, Excellent quality and this was one of those happy experiences during my TR restoration.

Cheers,

Waldi

OK thanks Waldi, and noted dimensions.

Think in this instance I will take your advice and get exchanged professionally. I will still endevour to be able to do this myself, I love an engineering challange, and we should be able to do this just as well.

Colin.

 

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I have always found an airbed adaptor, with the very end cut off ideal to shove into the injectors to allow you to blow out with an airline. Lots of injectors get sent for recondioning simply because of a bit of debris jammed inside that prevents bleeding.  Obviously the seals were shot in yours because they were rattling.

Once you have replaced the seal you can check the opening pressure if you have a compressor and a regulator.

If you have the correct tool (who does) you can adjust them without dissassembling - if you don't you take of the circlip pop apart with the compressed air, use an allen key to adjust, reassemble and test again - repeating until you get it right.

 

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1 hour ago, c.hydes said:

OK thanks Waldi, and noted dimensions.

Think in this instance I will take your advice and get exchanged professionally. I will still endevour to be able to do this myself, I love an engineering challange, and we should be able to do this just as well.

Colin.

 

 

1 hour ago, Waldi said:

Colin,

I made a note in my wsm. Think this info came from this forum:

Viton Grade B (not A), 75 Sh hardness.

OD: 5/16” (7,94 mm)

ID: 3/16” (4,76 mm)

Thickness: 1/16” (1,59 mm)
 

On these small diameters a tenth of a mm can be a lot, especially on thickness.

 As said, liberally lubricate.

I think Neil Ferguson charges less, he did mine, Excellent quality and this was one of those happy experiences during my TR restoration.

Cheers,

Waldi

Hello again Waldi.

I know that measuring o rings with a vernier caliper & micrometer is fraught with measurement & uncertainty errors, but I have remeasured mine again. They agree with your above ID and OD, but the CSA is definitely 1.79/1.80 mm. This is + 0.2 mm larger in CSA and hence maybe not completely seat in the o ring groove, and hence the very tight fit within the bore.

I do like Andy`s post describing his test methods and proceedures to replace and calibrate, will be trying to replicate.

Think more research is required.

Coli 

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1 hour ago, c.hydes said:

 

Hello again Waldi.

I know that measuring o rings with a vernier caliper & micrometer is fraught with measurement & uncertainty errors, but I have remeasured mine again. They agree with your above ID and OD, but the CSA is definitely 1.79/1.80 mm. This is + 0.2 mm larger in CSA and hence maybe not completely seat in the o ring groove, and hence the very tight fit within the bore.

I do like Andy`s post describing his test methods and proceedures to replace and calibrate, will be trying to replicate.

Think more research is required.

Coli 

Simply not worth the hassle, dirt will be your enemy send them to Neil and know they are good. 

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4 hours ago, ntc said:

Simply not worth the hassle, dirt will be your enemy send them to Neil and know they are good. 

+1. I get mine professionally rebuilt in Australia, you know the right components have been used and they are bench tested and sealed prior to dispatch. One less problem down the track.

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19 hours ago, ntc said:

Simply not worth the hassle, dirt will be your enemy send them to Neil and know they are good. 

Buying the correct seal is not difficult from the likes of Chris Witor. No need to measure them.

As for dirt ingress - a clean sheet of newspaper on your workbench is all that's required. I doubt any of the rebuilders do their work in the controlled environment of a semiconductor lab!

Dissasembly is a matter of carefully prizing off a circlip (I like the bag suggestion),  pushing the innards of the injector out  - someone has mentioned a bit of wood, I tend to use compressed air.

Remove o-ring, lubricate and put new o-ring on reassemble and put circlip on. Test opening pressure - should be between 45 and 55psi. A good injector should not dribble - apparently the test is it takes more than 1 minute for a droplet of fuel to form on the tip of the injector at 40psi. (Never done that one myself). If you can't get a good seal or get the injector opening pressure right then by all means send it off for rebuilding. If the injector was otherwise in good order you probably don't even need to check the opening pressure as swapping the o-ring shouldn't change that.

I wouldn't suggest rebuilding the metering unit at home but  there are those that do Good info on how the Lucas PI works

 

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1 hour ago, Andy Moltu said:

Buying the correct seal is not difficult from the likes of Chris Witor. No need to measure them.

As for dirt ingress - a clean sheet of newspaper on your workbench is all that's required. I doubt any of the rebuilders do their work in the controlled environment of a semiconductor lab!

Dissasembly is a matter of carefully prizing off a circlip (I like the bag suggestion),  pushing the innards of the injector out  - someone has mentioned a bit of wood, I tend to use compressed air.

Remove o-ring, lubricate and put new o-ring on reassemble and put circlip on. Test opening pressure - should be between 45 and 55psi. A good injector should not dribble - apparently the test is it takes more than 1 minute for a droplet of fuel to form on the tip of the injector at 40psi. (Never done that one myself). If you can't get a good seal or get the injector opening pressure right then by all means send it off for rebuilding. If the injector was otherwise in good order you probably don't even need to check the opening pressure as swapping the o-ring shouldn't change that.

I wouldn't suggest rebuilding the metering unit at home but  there are those that do Good info on how the Lucas PI works

 

Thanks Andy the PI Lucas document is very informative not seen that before.

Yes I agree, it isn`t that complicated, as long as all components are cleaned and reassembled in a clean environment. As stated my problem was getting the valve back in again, it was very tight

Waldi gave me some measurements for the o ring and mine from Chris Witor dont agree. Did you see this and can you confirm or comment from your expirence?

A member suggested soaking the o ring in petrol prior to fitting, do you do this?

Cheers, Colin.

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Done it a number of times.

If they are the injector o rings from Chris Wittor they fit unless he's sent you are the wrong ones by mistake - give him a call. I am assuming you have removed the old ones which tend to get crushed flat rather than fall out?

There's no benefit from soaking them in petrol - they are made of Viton which should be impervious to petrol. I tend to spray the inside of the injector with WD40 (or a blob of 20w50 from the oil can) when assembling. Once you get it in so far blow it the rest of the way with the airline with the airbed attachment. (Hold the injector in a cloth as the tips are pointed and as it shoots down the injector you feel it as it it hits your hand!)

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15 hours ago, Andy Moltu said:

Done it a number of times.

If they are the injector o rings from Chris Wittor they fit unless he's sent you are the wrong ones by mistake - give him a call. I am assuming you have removed the old ones which tend to get crushed flat rather than fall out?

There's no benefit from soaking them in petrol - they are made of Viton which should be impervious to petrol. I tend to spray the inside of the injector with WD40 (or a blob of 20w50 from the oil can) when assembling. Once you get it in so far blow it the rest of the way with the airline with the airbed attachment. (Hold the injector in a cloth as the tips are pointed and as it shoots down the injector you feel it as it it hits your hand!)

The O rings from Chris Witor were purchased about 5 years ago, and no receipts, they were cheep so not too bothered. when disassembled the valve just fell out and indeed were totally flat.

I don`t have any air source at present and thinking of getting a straight screw adaptor made to fit the thread (if we know what it is), to attach air line and guage.

Colin.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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