Do my injectors need servicing?

[Davydine]

Good morning,

I have a Thornycroft T90 engine which is a little reluctant to start. It needs at least 30 seconds of heat and then has to be cranked for about 10/15 seconds before starting. When it does start there is quite a bit of white smoke, which gradually reduces as the engine gets up to working temperature. The engine seems to have plenty of power, but since we have just got the boat I have nothing to compare with.

Do you think that the injectors may need servicing, and if so, can I remove them myself and can anyone recomend somewhere in the Essex / Suffolk area to get them serviced?

Also, can anyone recommend a good guide book to diesel engine maintainance to help troubleshoot problems.

Many thanks,
David

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[Talbot]

When this happens to my diesel engines in my cars, I know that I have to replace the glow plugs! I would try that and at the same time fill your secondary fuel filter with an injector cleaner rather than fuel. This should clean your injectors and allow much better starting.

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[scottie]

the area around the heater plugs can coke up and require cleaning this is done with ahand hel twist drill bit
check the w/s manual for size

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[Seal_surfer]

Try Diesco in Ipswich. Friendly, efficient and reasonable prices. Give then a call to get directions as they are hidden away behind the HGV MOT test centre off Landseer road in a residential road. They have made the odd check on injector FOC whilst I waited, and a complete nozzle replacement was ~ £25.

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[Trevor_swfyc]

Hi David,

From my limited experience it is well worth getting the injectors looked at, look in the yellow pages for a service agent local to you.
In Basildon Essex, I had mine fitted with new nozzels at:<pre> Fuel Injection Equipment Services
Harvey Road,
Burnt Mills Estate,
Basildon,
Essex.
Tel 01268 727672/727697</pre>

<pre><font color=red>
Bad starting is probably a combination of factors:
.
Loss of compression: Between piston and bore.
Valves badly seated and pitted.
.
Poor atomization of fuel: Pre heat failure.
Injectors worn.
Injector fuel pump problem.
Low air temperature.</font color=red></pre>

Apart from new nozzels I also decoked the head and reseated the valves, my poor starting Volvo 2002 now starts on the button. Total cost under £200, the Volvo head gasket price came as a shock, but it was money well spent.

Good luck.
Trevor



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[Guest]

Common one forgotten here

Sticky rings. THis allows poor compression and poor starting. But ince warmed up she seals better.

My diesel has sticky rings and is exactly same as you describe.....


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[PeteMcK]

Try:
http://www.boten.nl/motoren/motoren_pdf/bmc_tempest.pdf
(BMC 1500 Tempest - same engine)
or (10 meg!):
http://www.instruction-manuals.co.uk/category/tractors/BMCminiT.htm
(Leyland 154 tractor - again, same engine)
and the followng may or may not work:
http://www.semidiesel.com/olm/pdfs/bmc1500.pdf
I've asked Rover for permission to put my copies of the Thornycroft handbooks and parts manual on the web but got no response.

Sounds to me like your heaters are not all connected (most likely and probably just dirty or corroded electrical connections) or some may be dud, or your timing is too far retarded. The injectors don't really tend to go off, and not all at once, and if the engine is otherwise running ok, I'd look elsewhere. Be careful if you decide to change the heaters: you can break them if they're seized and then your looking at a messy head off job.

The T90 book says:

According to the Thornycroft (i.e., Leyland) book,

"Whenever the engine is started from cold:

.....
4) Open throttle fully, ensuring that the gearbox control lever remains firmly in neutral.

5) Turn the starter switch to the 'HEAT' position for 30 seconds.

.....

With a warm engine, it will not be necessary to stop in the 'HEAT' position or to have the throttle fully open."

Note that, from cold, you need to heat for much longer than you do with modern car diesels. The white smoke is just from unburnt fuel that's collecting in the cylinders and in the exhaust prior to the engine firing.


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[charles_reed]

From the picture painted I'd not bother about doing anything about the injectors yet.

Whilst those old BMC diesels were always reluctant to start, yours appears slightly worse than most.

I'd suggest looking at the preheater plugs, as the most likely cause, followed by checking whether or not coolant levels are dropping - you may have a leak from water-jacket into one cylinder.

Like motherhood and apple-pie its always a good idea to have your injectors set up once in a while, I usually do it as a matter of course when I do a top-end overhaul and decoke after about 1000-1200 hours run.

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[tonykerry]

Hi David, I had the same problem with my T90 but a set of new glowplugs cured it completely. It now starts every time with the engine at tickover after 15 secs heat. While I had the glowplugs out I checked the compression on each cylinder and it was 400 psi on each. The main difference after fitting the new glow plugs was that initially on the heater switch position the ammeter discharges to max, but recovers in a few secs to a normal discharge. Tony Kerry

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[boatmike]

Agree with others but I am concerned that the white smoke actually sounds like steam and could be a coolant water leak. If the injectors are all clean and all heater plugs working (check these first) I would personally have the head off and take a look. You may find the gasket shows water leaking across from jacket to cylinder. If this is serious you could notice coolant levels going down and possibly water in the oil making it like a white emulsion. In really severe cases the water level goes down and the oil level goes up! Also check valves for seating. Burnt valves= poor compression, so do stuck rings. Not a bad plan to hire a compression tester to check compression on each cylinder in turn before ripping it apart...
Another cause of water in the cylinders at start up is syphoning in the exhaust. Do you have an anti-syphon valve in your exhaust? if so is it working? If not when shutting down next time you run the engine try slackening off the manifold screws to break the air seal on the exhaust outlet just before you stop the engine. tighten again before you start next time and see if the trouble persists. Do one thing at a time though or you will never know what cured it!

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[Davydine]

Thanks for this. I have decided to replace the glow plugs anyway as they are not terrible expensive and hopefully this will help starting. I recently changed the oil and there was no evidence of water, however I will keep an eye on the coolent water level. Interestingly when I checked this for the first time it was very low and since buying the boat I have hardly run the engine as I have been doing other jobs.

I am tempted to bring the engine home this winter for an overhaul when the boat is layed up. If I do I will change the head gasket as a matter of course.

Hopefully this will solve all of the problems!

DW

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[sailorman]

Diesco in ipswich

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[VicS]

Check the glow plus indivdually with a meter set to ohms, after disconnecting the wiring. A good glow plug will have a very low reistance a failed one will be infinite.
If you are happier with a bulb connect each in turn to the battery via a low wattage bulb. If the bulb doesn't light the glowplug is o/c.

If you take them out a failed glow plug will be covered in carbon so is easy to spot before confirming with the meter.

Be careful as any good ones will be very hot if youv'e just had them swiched on.

<hr width=100% size=1><font color=purple>Ne te confundant illegitimi.</font color=purple>

 

[boatmike]

Don't forget to check for syphoning though. What happens if I am not teaching granny to suck eggs is that when the engine cools down water is sucked back up the exhaust to the valve chest unless there is an air bleed in the manifold to prevent the syphon.... Often these are fitted with valves that get blocked if they are not cleaned. I much prefer the ones with no valve and an overboard discharge as no one ever cleans the valves.... Very common problem and very simple to fix.
Also one other thing I would check. If you have rubber exhaust pipe the inner pipe can sometimes get detatched from the outer at the reinforcement and close up creating back pressure. You cant see it. no one believes it happens 'cause the pipe looks OK on the outside, but I would like a fiver for the number of cold start problems I have traced down to old perished internal pipes closing off the exhaust..... Unlikely but you would kick yourself if you stripped the engine down first and it was a £10 lump of pipe all along.....
Good luck!

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[oldharry]

Glowplugs. Dont touch anything else until you have had them out and checked them.

Connect a heavy wire to the terminal and back to the Pos pole of the battery. Hold the plug in a molegrips (it gets Very hot!) and touch the plug body to the negative battery pole. The plug should develop red heat within a few seconds. If it works, and the tip is not damaged, its OK. There will be sparks as well as they draw a big amperage, so make sure there is nothing flammable around!

The white smoke is almost certainly unburnt diesel mist from the injectors, caused by the cold engine not igniting the fuel.

Engines will usually start on 3 out 4 plugs operating, but when 2 plugs fail, starting becomes very difficult, and the engine will produce volumes of white smoke, just as you describe once it fires.

As long as this clears within about 30 seconds of the engine running evenly after a cold start, there is nothing else seriously wrong.

If white smoke continues to appear, then there are other problems which can be injectors, low compression (see Nigel Luthers post), or a fuel line fault - partial blockage, air leak etc. If the engine runs smoothly and well once it is warm, and there is no appreciable blowby (causing excess crankcase pressure) then there is nothing that warrants tearing to pieces!

Injectors are easily removed usually (but not always - they can stick, which causes much grief and head scratching!), and can be taken to an injection specialist for testing and re-setting. Make sure you retrieve the copper flame guard washer that goes at the base of the injector, and get new ones. Leaving them out, or putting two in can cause all kinds of interesting problems! You can sometimes get away with re-using them, but will almost certainly get a compression leak past the injector. Dont whatever you do bend the injector pipes out of shape. If you do they will fracture when the engine is running, in a few weeks time. They must not be stressed in any way, so release them at both ends to move them clear.

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[PeteMcK]

If you're going to take the plugs out, you should take the chance to clear the carbon from the holes by turning a drill by hand: diameter 11/64 inch says the book! Alternatively, I squirt in Holts Instant Decoke and leave it over night but I'm not sure that it's still marketed (RedEx might help to soften it too). If you don't, the carbon prevents the combustion air from circulating freely over the plugs.

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