Lotus Elan

Running getting worse

PostPost by: robertverhey » Thu Jun 02, 2011 1:17 pm

It's possible for a chain to loosen up once run-in and everything settles into place. To see if that's where your rattle is coming from release the lock nut on chain tensioner and slowly tighten the chain with engine running.....if the rattle gets quieter then you'll know that's the problem. If you go too far it will start to whine.

Once you've verified that the chain is where the rattle is coming from, I'd be inclined to tension it properly, with cam cover off and so that there's 0.5" play up and down in middle of chain's top run
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PostPost by: Robbie693 » Fri Jun 03, 2011 9:23 am

Thanks Robert,

I do intend to take the cover off and set the chain tension. Is there anything else I should be looking for that could account for the sudden rattle? The chain isn't new by the way, last time I adjusted it was after doing the head gasket.

Cheers

Robbie
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PostPost by: neilsjuke » Fri Jun 03, 2011 9:37 am

I would mark the chain and do a full rotation to check in case it has a joining link that is about to let go.
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PostPost by: Robbie693 » Fri Jun 03, 2011 2:05 pm

Thanks Neil,

It does have a split link chain - will it be obvious if something is amiss?
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PostPost by: Robbie693 » Thu Jun 09, 2011 3:54 pm

Another update -

I have checked the fuel tank outlet for crud, there were a couple of flakes inside the banjo bolt but nothing too serious. There was no filter in the tank so I presume this was discarded at some point. Apparently Paul Matty remove them if they find them.

I checked the timing chain and it was a bit slack, maybe 1/4" too loose so I have re-set to 1/2" total play. Also checked the valve clearances and all were in spec apart from no.4 exhaust which was .0085, i.e. 1/2 a thou too tight. Is this a problem?

This didn't cure the rattle but, with the aid of my 'stethoscope' (screwdriver) it sounds like the alternator bearings have gone so I've ordered a new 45A one.

None of this has had any effect on the refusal to rev problem however...

I was going to take it to Aldon to see if there are any ignition bits breaking down under load but I don't have the time at the moment. I'm still thinking of trying another coil, also maybe another distributor cap after reading this thread:

http://www.lotuselan.net/forums/elan-f15/stops-when-hot-why-t22622.html

Specifically:
With the demise of Lucas, many of the pattern parts available for the ignition system seem to be of poor quality and either fail after a short period, or don't work at all (many would argue it wasn't much better when Lucas were still going)

I suffered exactly the symptoms you describe, and after a great deal of hassle traced it to the distributor cap - which became conductive when hot. I tried three or four caps from different suppliers, but all had been sourced from the same manufacturer, and all had the same problem. The tell tale sign was a small square moulding sprue on the top of the cap.

As others have pointed out, your problem could be coil, dizzy cap, condensor, rotor arm or leads. Any of these components can fail when hot, only to come back to life when they have cooled. The morale of my tale is if you are trying to find the fault by substitution, dont assume that new components are going to work any better than the originals, they could even be worse.


I am trying to remember when the last time was that I definitely remember not having this problem. I think it was fine before I did the head gasket. I had trouble getting it to run on all four cylinders after this and in my attempts to fix it I replaced the distributor cap and leads and the plugs. Then I gave it to Paul Matty who found it was just the carbs out of balance :oops: . They also replaced the distributor as I noticed the body had cracked and had had a piece glued in.

So the only changes after the head gasket were the Distributor, cap, leads and plugs. The plugs have been replaced since so I'm left with the possibility of the new cap, leads or distributor being faulty I guess.

As you've probably gathered I am resisting the temptation to go to electronic ignition at the moment because I'm dying to know why it won't work now when it did before! Also the last Plus 2 I had ran fine on points for years.

I know. I'm going round in circles.

Sorry if this is becoming a blog

Can anyone recommend a supplier of quality distributor caps without the aforementioned 'sprue'?

Robbie
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PostPost by: Robbie693 » Wed Jul 27, 2011 2:54 pm

Hmmm, Well hopefully without tempting fate I think I've fixed it!

Only done a brief test so need to see how it goes and if the revving problem returns, fingers crossed and I hope the car doesn't hear this :D

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PostPost by: gjz30075 » Wed Jul 27, 2011 4:21 pm

Details forthcoming?

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PostPost by: pauljones » Wed Jul 27, 2011 5:50 pm

Has it by chance not been Put back correctly, im thinking perhaps the little pig tail has not been installed wrongly.!
Kick the tyres and light them fires...!!!!!!!
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PostPost by: Robbie693 » Thu Jul 28, 2011 9:39 pm

Sorry to be a tease, I didn't want to offer a solution to the problem without testing it a bit first.

Anyway, all I did was wrap the coil with that heat proof adhesive tape stuff.

My theorizing went like this - as I mentioned previously I was trying to remember when it was last ok and what I did to it to cause the problem. When I changed the head gasket I replaced, amongst other things, the bottom radiator hose. I noticed at the time that the new one was quite a bit thinner in wall thickness than the old one but paid it no mind. When I fitted the new coil I went to great pains to keep it away from the bottom hose but it was still pretty close at the bottom (I didn't want to drill any more holes in the wing). So my theory was that the new bottom hose, being thinner, radiates more heat and the coil, being in such close proximity was getting cooked once the engine was up to temp and breaking down at high rev's. Hence the problem only happening when the car was hot...

So the heat proof tape seems to have made a difference - I drove it today and it was pretty warm weather, 25 deg or so, and the engine was hot from sitting in traffic. When I had a chance to floor it the engine ran round to the red line with no hesitations, coughs or cutting out!

Still going to keep testing until I am convinced though...

Thanks to everyone for their help with this, at least with all the checking I've done I know that those bits are ok. For now... :D

I'll be back if there is a return of the symptoms!

Cheers

Robbie
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PostPost by: paddy » Fri Jul 29, 2011 9:40 am

Remember that the coil will heat up by itself and the heat-proof tape will stop heat getting out as well as getting in. I would also try insulating or shielding the hose in some way, and leaving the tape off the coil to allow it to stay cool.

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PostPost by: Robbie693 » Fri Jul 29, 2011 9:59 am

Thanks Paddy, I did wonder about that.

I'm wondering if an aluminium shield will have the same cooling effect as the tape.

Cheers

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PostPost by: bcmc33 » Fri Jul 29, 2011 10:13 am

Robbie693 wrote:Sorry to be a tease, I didn't want to offer a solution to the problem without testing it a bit first.

Anyway, all I did was wrap the coil with that heat proof adhesive tape stuff.

My theorizing went like this - as I mentioned previously I was trying to remember when it was last ok and what I did to it to cause the problem. When I changed the head gasket I replaced, amongst other things, the bottom radiator hose. I noticed at the time that the new one was quite a bit thinner in wall thickness than the old one but paid it no mind. When I fitted the new coil I went to great pains to keep it away from the bottom hose but it was still pretty close at the bottom (I didn't want to drill any more holes in the wing). So my theory was that the new bottom hose, being thinner, radiates more heat and the coil, being in such close proximity was getting cooked once the engine was up to temp and breaking down at high rev's. Hence the problem only happening when the car was hot...

So the heat proof tape seems to have made a difference - I drove it today and it was pretty warm weather, 25 deg or so, and the engine was hot from sitting in traffic. When I had a chance to floor it the engine ran round to the red line with no hesitations, coughs or cutting out!

Robbie,

If you had said this to my face - I would have laughed out loud. :D

I would have thought that insulating the coil is the last thing you should do as the internal heat stands a good chance of boiling the oil at a greater temperature than could be radiated from what should be a relatively low temperature bottom hose.

But then, what do I know?

EDIT: P.S. Sorry, I seemed to have been a bit late in sending this message.
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PostPost by: Robbie693 » Fri Jul 29, 2011 10:28 am

bcmc33 wrote:Robbie,

If you had said this to my face - I would have laughed out loud. :D

I would have thought that insulating the coil is the last thing you should do as the internal heat stands a good chance of boiling the oil at a greater temperature than could be radiated from what should be a relatively low temperature bottom hose.

But then, what do I know?

EDIT: P.S. Sorry, I seemed to have been a bit late in sending this message.


:D

Funny how these things seem to make sense in hindsight!

Not had any trouble so far, I insulated the top and bottom of the coil but left the bit under the bracket, mainly for earth contact but maybe this is providing sufficient cooling...

I have some sheet aluminium so will attempt a heat shield around the bottom hose.

Or i suppose I could re-fit the original but tatty hose.

Off to South Lincs tomorrow so I guess that will be a more thorough test as it looks like the weather will be warm.

Regards

Robbie

PS I have a spare coil in the boot!
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