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Disco V8 woes


Pwyll

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Just when I thought it was all going so well!

After a bit of a long story, I finally managed to get my Disco to run and pass an MOT.

It turned out the distributor was worn and needed replacing. Fine, off to try and find one. Turns out the only way to get them new is from Britpart through local Landrover stealer. So my tame mechanic put that in for me and, after a few teething problems, all was well.

I have done nearly 300 miles around South and Mid Wales over the weekend and it didn't miss a beat.

SWMBO borrowed it this morning to move her horsey gear around. Mid morning I got a call to say that it had cut out. No missing, no popping and banging, just revs died off and stalled. I came home from work, but by this point it was running again. As she didn't want to be stuck on her own we parked it up and waited until I could finish work proper and be with her.

Once I returned, it fired up and ran ok, so off we went. Half a mile or so it stalled again. Re-started and another 100 yards stalled again. Decided to head for home at this point. Turned around at roundabout, only running for a couple of seconds at a time now. Then it finally gave up the ghost. Turns over fine, but will not fire. There doesn't seem to be any spark at the plugs (took a lead off, put a screwdriver in and held close to block).

I am not brilliantly mechanically minded. but I have a few basic trains of thought. Either it is the distributor (having heard the horror stories about Britpart) or the spark is not getting as far as the distributor in the first place.

How would I go about checking that there is power going into the coil? I have a basic multimeter, but no clue as to where I should be checking.

If there is power into the coil, is there a way of checking that it is being transfered to the distributor?

One other option that has popped into my head is the imobiliser, but I didn't think this would give the intemittent and then total failure. Could I be wrong?

It is a 3.9 EFI autobox, if that makes any difference.

Any help or advice would be gratefully recieved.

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It could be the spider i had the same problem but only found out after replacing the coil ,amplifier,leads,dizzy cap & rotar try putting direct power from the battery to the + on the coil if it starts and runs I would think it is dry solder in the spider easy fix when you get it out from below the radio it is the we black box

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Check for loose connections on the low tension side of the coil, there should be a black/white wire fitted, if this is loose the ECU won't see a spark and cut the fuel.

Also, the problem sounds like it could be the ignition amp -swap this for your old one if you can, it's the little black box on the side of the dizzy with 2/3 wires coming out of it.

Power to the coil is easy, turn ignition on and measure across the low tension(small) terminals.

Spark to the dizzy is also easy, pull the centre lead off the cap, hold it close to the engine block and get a helper to crank the engine, there will be 4 sparks per engine revolution, so should be easily noticeable -just hold it in something insulated!

You can then do the same with one of the plug leads to check the internals of the dizzy.

Another quick check is to whip the cap off and check the rotor arm is still in one piece, and the carbon brush in the top of the cap is still in place.

HTH somewhat :)

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It's also not entirely dissimilar to the symptoms you might expect of coil failure - quite often they're ok for a bit, then cut out. If you wait it all recovers & comes back for a bit longer and the cycle repeats. You may have a cold start coil, ie with a ballast resistor - in that case worth checking that the cold start feed (to the coil side of the ballast resistor) is cutting out when the starter is off, and that the ballast resistor isn't short circuited, as that might upset a healthy coil.

Nigel

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If the ignition amplifier wasn't changed with the distributor, I'd strongly suspect that as a first point of call. They fail with heat, so you will get the "cutting out after a few miles, restarts and runs for a bit if left for a bit" symptoms.

It's not a complex system so take a methodical approach and I'm sure you'll sort it soon enough.

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Now the rain has gone away for a while, a chance to delve further.

In answer to the above, the amp was originally next to the coil. But the new distributor has one strapped to the side so the wiring was extended to reach.

There is power coming into the coil. About 11.8V, probably a bit low because the engine has done a lot of cranking and bugger all firing.

After doing a little web research I tested the resistance of the two windings. Primary comes in at 1.1 ohms and the secondary at 4850 ohms. According to Haynes, the primary is ok (0.5<>1.2) but the secondary is out of range (3000<>4000). Not knowing the tolerances on these sort of things I am unsure what this tells me. My hunch is that the coil is bust. Correct?

I humbly await your wisdom. Particularly as SWMBO wants to use it for work tomorrow evening!

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And the saga continues....

It does not appear to be the coil as a new one hasn't cured the problem.

Next move was to run through BogMonsters "how to" on the spider. Trouble is - no spider.

There appears to be an aftermarket alarm fitted. The box next to the fuseboard has "Serpistar GM300" written on it and the logo matches the sounder under the bonnet. The only info I can find on it doesn't seem to relate to this specific model so I am reluctant to start trying to fiddle with it.

I am at a bit of a loss as to where to go next. My gut feeling is that the next week link is the amplifier on the side of the distributor, but taking that off means taking the distributor out. If this is unavoidable, then so be it. But if there is something I'm missing that anyone could point out I would be very grateful.

BTW, I have just checked all the fuses that I could find and all are ok.

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It does look very like the amplifier then, if the coil has power but its not sparking then either the VR sensor in the dizzy is broken or misaligned, or the amp is duff

I'd consider doing the GM HEI mod i linked to further up the page.

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Well, it's running again, not perfect, but running.

New amplifier seems to have done the trick. I marked the distributor up as best I could and lined it up again when it went back in but there is still some "lumpyness" there somewhere.

I will double check eveything again tomorrow and if that doesn't cure it then it's onto the trailer and into a garage and I will miss another oportunity to try out the new trialler I bought three months ago.

But, hey ho, life goes on.

Thanks to all for the advice.

Aragorn, ref the mod, it would be nice but I'm not really confident enough to do it myself at the moment. All I want is a truck that goes for now.

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One of the best mods to a D1 igniton system is to fit a Scorcher distributor made by Perfomance Igniton Systems in Melbourne. It is custom made and curved to suit your exact engine requirements, using common and cheap to replace Bosch parts, including Bosch cap and rotor, new body, correct drive gear. Costs AUD600 - less than a 123 or MSD. Provides a significant improvement in performance over the Lucas options and is far more reliable than a Mallory. Can be done in three days.

www.performanceignition.com.au/scorcher-distributors

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If your talking about changing the distributor, i'd just go Megajolt- it'll be cheaper and better. I'm in the process now!

Hope you get it sorted. When a problem drags on and on through endless troubleshooting it can be a real bummer... :wacko:

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I agree. When it comes down to replacing the dizzy then megasquirt/jolt is the way to go.

You will need to get a timing light and scope out the static advance to ensure its right, simply putting it back on the marks may not be good enough.

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