ThreePointFive Posted January 24, 2011 Share Posted January 24, 2011 Hi all, One of the spark plugs on my 3.5 V8 is held by what's left of the threading on the block as I over tightened it at the last service, but it is possible to spin it if tightened too far. For a good number of months this was no issue, but recently the car has been stalling a lot while being driven on the road, which seems to be coinciding with the spark plug coming loose each time. I can tighten the plug enough that it is held and can't be tightened or loosened by hand at all, but i want to avoid over-tightening to destroy whatever is left of the thread. This problem has so far been at relatively high speeds, around 50mph with no reason for the stall at all, and after the engine has been running for a good length of time, over half an hour in both the times it has happened. Is there any way to repair the thread on the block? Someone on another forum mentioned heli-coiling, would this be the recommended option from the V8 gurus on here? Can the stalling be linked to this issue? The car wasn't being used often when it was happening (it's currently off the road) and so I thought fuel may be the issue, but the tank is clean and there's nothing in the filter to cause concern. Air filter is likewise clean. Any help appreciated. Quote Link to comment Share on other sites More sharing options...
stuck Posted January 24, 2011 Share Posted January 24, 2011 Heli-coil would be your only option I think apart from a new head. Wouldn't have thought one plug coming loose would cause it to stall on the move though. Hopefully a sensible person will be along soon. Quote Link to comment Share on other sites More sharing options...
western Posted January 24, 2011 Share Posted January 24, 2011 Heli-coil insert repair should work fine. Quote Link to comment Share on other sites More sharing options...
Quagmire Posted January 25, 2011 Share Posted January 25, 2011 Have you got an electronic dizzy? Could be a bad amp as it sounds like it is only happening when its warm. Or maybe a bad coil? Does it restart right away from the stall, or do you have to let it cool down? I had a plug come loose on me once from doing the opposite and not tightening enough! The engine ran ok, and i seem to have got away without it tearing the threads out under compression. The only symptom I had with this was it was dropping to 7 sometimes and on inspection when running the plug lead appeared to be vibrating as the plug moved in and out slightly. Quote Link to comment Share on other sites More sharing options...
ThreePointFive Posted January 25, 2011 Author Share Posted January 25, 2011 Thanks for the replies. I thought all Dizzy's where electronic?! It has to cool down a bit before it will restart, not by much but it has never just restarted straight away. It's never done it more than once, seems after the first time it sorts itself out, though obviously I get back home as fast as I can after the first time. The plug does appear to move in and out slightly when this is going on, so I know it is coming loose. It doesn't sound like this will be the issue then... Quote Link to comment Share on other sites More sharing options...
Quagmire Posted January 25, 2011 Share Posted January 25, 2011 Sorry- by electronic I mean it has a reluctor wheel inside and no points. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 25, 2011 Share Posted January 25, 2011 Carbs or EFI? Quote Link to comment Share on other sites More sharing options...
ThreePointFive Posted January 25, 2011 Author Share Posted January 25, 2011 Carbs - it's a 1988 factory fit V8. Afraid I don't know about things like points! Quote Link to comment Share on other sites More sharing options...
mickeyw Posted January 25, 2011 Share Posted January 25, 2011 Carbs - it's a 1988 factory fit V8. An engine from this era should have an electronic dizzy. Quote Link to comment Share on other sites More sharing options...
JeffR Posted January 25, 2011 Share Posted January 25, 2011 If its the correct dizzy then change the amplifier pack do the plugs, cap, rotor arm and leads and coil while you are on- when mine died it buggered the lot. The intermittant misfire was an absolute hoot - 3 foot jets of flame from the exhaust! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 26, 2011 Share Posted January 26, 2011 You can fit a much better GM amplifier module in its place for ~£25 and some minor tweaks to the wiring, there's a link somewhere round here to the V8 Capri forum where they wrote it up. I did it on my RR and it ran a 0.7 Ohm sports coil quite happily. Quote Link to comment Share on other sites More sharing options...
ThreePointFive Posted January 28, 2011 Author Share Posted January 28, 2011 Thanks for the replies, very interesting reading. So it's likely to be dizzy related rather than anything else? That does surprise me, given the intermittent nature of the problem! I'll have to look into this, I need the car to be 100% for getting back on the road ASAP. Quote Link to comment Share on other sites More sharing options...
JeffR Posted January 29, 2011 Share Posted January 29, 2011 By intermittant I actually mean every 1000 miles. Literally to the mile a miss fire would occur, resulting in no power and 3 foot jets of flame. The temp fix was to change the rotor arm (now got a box full of the buggers).This, as you would imagine , got to be a pain so set about changing everything. One word of warning, there are cheap coils and there are good coils, my V8 will not work with cheap OE coils, use genuine Bosch, more expensive, but work. Quote Link to comment Share on other sites More sharing options...
ChrisJones117 Posted January 29, 2011 Share Posted January 29, 2011 Hi all, One of the spark plugs on my 3.5 V8 is held by what's left of the threading on the block as I over tightened it at the last service, but it is possible to spin it if tightened too far. For a good number of months this was no issue, but recently the car has been stalling a lot while being driven on the road, which seems to be coinciding with the spark plug coming loose each time. I can tighten the plug enough that it is held and can't be tightened or loosened by hand at all, but i want to avoid over-tightening to destroy whatever is left of the thread. This problem has so far been at relatively high speeds, around 50mph with no reason for the stall at all, and after the engine has been running for a good length of time, over half an hour in both the times it has happened. Is there any way to repair the thread on the block? Someone on another forum mentioned heli-coiling, would this be the recommended option from the V8 gurus on here? Can the stalling be linked to this issue? The car wasn't being used often when it was happening (it's currently off the road) and so I thought fuel may be the issue, but the tank is clean and there's nothing in the filter to cause concern. Air filter is likewise clean. Any help appreciated. Google ' Timesert ' these are awesome, we use them at work for both Engine repairs and for stripped suspension / engone mount repairs. Rock solid, never had one fail in five years of using Quote Link to comment Share on other sites More sharing options...
Arbman Al Posted January 30, 2011 Share Posted January 30, 2011 Google ' Timesert ' these are awesome, we use them at work for both Engine repairs and for stripped suspension / engone mount repairs. Rock solid, never had one fail in five years of using I would second that - better than helicoils for spark plug threads. Quote Link to comment Share on other sites More sharing options...
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