Melted 1y diesel injector seal

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Cdm181070
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Melted 1y diesel injector seal

Post by Cdm181070 »

I have just fitted a 1y engine with reconditioned injectors and pump, It has just been running in the workshop and only driven around a yard. The engine had an exaggerated diesel knock and required 10 approx seconds of cranking  to start if left for about 10 min from normal operating temperature. I’d did start straight away with 6 seconds of glow plug though. I checked the compressions, my gauge read 450 on each cylinder. I did notice that 1 cylinder had melted the injector seal centre so the hole was enlarged to about 8 mm. I then arranged the fuel pipes on the pump so that I could mount and observe the spray patterns and 1 injector looked a bit narrower and maybe off to one side, but that wasn’t the one that had melted the seal, in fact that one looked ok, any ideas what may have caused the melting? And  the loud diesel knock? And the poor warm startup? Thank you. 

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Re: Melted 1y diesel injector seal

Post by colinthefox »

It seems to be very common for even perfectly good 1.9 engines to need a shot of glow to start warm. My AEF certainly did. You can achieve this by putting a 470 ohm resistor in series with the temp sensor in the back of the cylinder head. As for the knock, a poor spray pattern could be the cause. You could narrow down the knock to one cylinder by slackening each of the injector pipe nuts in turn and noting the one which makes a difference to the knock, then have that injector looked at. Water or bugs in the fuel can also cause knocks, usually associated with copious thick grey smoke, but that would affect all cylinders. I don't know what could have caused the burnt out fire washer. Never had that problem. Maybe a combustion leak past the fire washer could burn it.
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Cdm181070
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Re: Melted 1y diesel injector seal

Post by Cdm181070 »

Thanks for the tips, I’ve got the injectors out now so going to have them tested tomorrow. Thinking about it I did zinc plate the injector pipes and am now wondering if some of the zinc made it into the pipes, so thinking of changing them. Do you know if the 1.6d will fit the 1.9 1y? The 1.6d ones are easy to get. Thanks.

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Re: Melted 1y diesel injector seal

Post by colinthefox »

Cdm181070 wrote: 28 Mar 2021, 20:00 Do you know if the 1.6d will fit the 1.9 1y?

Sorry, can't help you there.
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Re: Melted 1y diesel injector seal

Post by silverbullet »

Cdm181070 wrote: 28 Mar 2021, 20:00 Thanks for the tips, I’ve got the injectors out now so going to have them tested tomorrow. Thinking about it I did zinc plate the injector pipes and am now wondering if some of the zinc made it into the pipes, so thinking of changing them. Do you know if the 1.6d will fit the 1.9 1y? The 1.6d ones are easy to get. Thanks.
Zinc plating doesn't reach down inside tubes very far at all, probably only a few mm at best on an injector pipe.
My IDI experience is limited, I would replace all the injector seals and see how it behaves.
They are only thick copper washers afaik.
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Re: Melted 1y diesel injector seal

Post by mrhutch »

when you say "injector seals" do you mean the flame traps?
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Cdm181070
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Re: Melted 1y diesel injector seal

Post by Cdm181070 »

Hi, that’s it. I realised after cleaning them up there are two different injector heat shield sizes, one with a small hole Approx 3/16” and another with approx 5/16” hole and it doesn’t matter which one you use I believe. I have since done some more troubleshooting on the engine. I did a compression test again and got the following results.

Cyl 1 = 530 PSI
Cyl 2 = 520 PSI
****** Cyl 3 = 440 PSI. ******
Cyl 4 = 520 PSI

Note. My compression tester was cheep so I’m thinking it may be reading high, but cyl 3 is different.

Note. The engine has had a Febi cam and followers before fitting the engine as I stupidly broke the slot in the end of the cam using it to turn the cam. Learnt the hard way.  The engine has ran for a few hours after this so thinking the tappers should be bled by now.

The fault I have is an intermittent misfire on what sounds like 1 cylinder. The engine starts from cold, sputters a bit at first and then runs ok, but when it gets somewhere around operating temperature it sounds like it drops a cylinder and then after some revving  it goes away for a while, sometimes it doesn’t do it . I am now thinking that the lower compression on cylinder 3 is maybe something wrong with the valves, maybe sticking or bent, and maybe the loss on that cylinder can go worse at times causing a misfire. I have ordered a cylinder leakage tester to quantify the loss and pin down where it is going. I bought the engine second hand and have never heard it run before this. I took a gamble as they are such a reliable engine. 

also

I have had my fuel pump and injectors reconditioned before fitting the engine. The fuel pump had some electronics on it for advancing the timing when cold, I had this put back to manual choke and all the electronics removed. I set the timing with a DTI to around 0.9 mm. As the pump has been heavily modified I would like to confirm the timing with a diesel timing light. My question is does anyone know the injection timing BTDC in degrees? It would be nice to confirm the timing is still right after the modifications. I have also had the injectors retested to make sure they are ok.

Thankyou.

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Re: Melted 1y diesel injector seal

Post by colinthefox »

I think you should test the tappet clearances with a feeler gauge. Leave the engine for a few hours after running, then push down firmly on the tappet and try to insert a 5 thou feeler gauge under the cam with the lobe pointing up. If there is no clearance on one of the exhaust valves then you should suspect a dropped valve seat. The seat comes loose and rotates its way back into the head till the clearance is zero. Depending on the relative temperatures of the valve stem and head, the valve will either just about seal or not, hence the variation in the symptoms.

I think if it was a badly burnt or bent valve there would be next to no compression on the cylinder.

As I don't have any experience of the specifics of that injection pump, I can't help with the timing I'm afraid.
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Cdm181070
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Re: Melted 1y diesel injector seal

Post by Cdm181070 »

Thankyou for the advice. Your loose valve theory fits my symptoms perfectly. I'm going to do a cylinder leak test on Saturday to see what the loss is and maybe where it is going.

I will also check the Clearance of the valves to see if that shows anything and post the results.

If a valve seat is loose is the cylinder head written off? Also does it affect the valve stems?

Thankyou.

colinthefox
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Re: Melted 1y diesel injector seal

Post by colinthefox »

I suspect that a loose seat is usually caused by a crack in the head casting  between the valve seats, in which case the head will be a write off. Only suspect this if you have no clearance at all on the suspect valve. I can't remember what caused the dropped valve seat on my CS engine 17 years or so ago.
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