Exhaust clamp leak causing starting problems?

Discuss mechanical problems here.
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
Post Reply
barry young
Minor Friendly
Posts: 31
Joined: Mon Jun 21, 2010 2:07 pm
MMOC Member: Yes

Exhaust clamp leak causing starting problems?

Post by barry young »

I've got a gas leak from my manifold to exhaust pipe clamp which I expect is causing the spluttering acceleration but Ive also suddenly got an intermittant starting problem where twice in the the last couple of days I couldn't get the engine to start. I left it for ten minutes and it started instantly. Could the gas leak be causing this too? (There's a spark at every plug, the smell of petrol and the pump ticking over, the coil's a few months old, distributer doctor points and condenser, new ht leads.)

Any help greatly appreciated.
ManyMinors
Minor Legend
Posts: 2752
Joined: Tue Nov 11, 2014 9:41 am
MMOC Member: No

Re: Exhaust clamp leak causing starting problems?

Post by ManyMinors »

I don't see why it should cause problems with starting but a loose exhaust clamp and escaping gasses can quickly cause poor running if the air filter gets blocked with soot. That is something worth looking at - but the best advise would be to sort out the exhaust asap!
myoldjalopy
Minor Legend
Posts: 2518
Joined: Tue Jan 29, 2013 10:32 pm
Location: Kernow
MMOC Member: Yes

Re: Exhaust clamp leak causing starting problems?

Post by myoldjalopy »

I agree with 'ManyMinors' that a leak at the exhaust/manifold joint shouldn't stop the car starting. It might well cause it to pop a bit on the overrun. But assuming everything is set up properly (timing, plug and points gaps, carb, coil connections etc.) the clue might be in your comment 'the coil's a few months old'..........many modern coils are prone to failure, sometimes intermittently which is always a nuisance in diagnosis.
So, sort the leak and I'd be tempted to swap out the coil for a known good one and then see what happens.
oliver90owner
Minor Legend
Posts: 1653
Joined: Thu May 12, 2016 6:33 am
MMOC Member: No

Re: Exhaust clamp leak causing starting problems?

Post by oliver90owner »

It could be fuel mixture or ignition.

The ten minute wait could either have allowed a flooded engine to dry out, or a failing coil to cool down.

Certainly the poor start is nothing to do with a small leak - if it did, many would never get their engines started when the vehicle has an exhaust failure!

First thing is to immediately check for a spark (and spark quality, if their is one) when this ‘intermittent’ faults arises.
barry young
Minor Friendly
Posts: 31
Joined: Mon Jun 21, 2010 2:07 pm
MMOC Member: Yes

Re: Exhaust clamp leak causing starting problems?

Post by barry young »

Thanks for the comments, everyone. I've sorted the manifold leak but the starting problem persists.
Using an Acuspark cap I can see a big beefy flash when the engine is running but a very little one when starting. The battery is fully charged and connections are good. It's easier to start when the engine is warm but sounds like it's not initially running on all cylinders and there's the smell of unburnt fuel.
This is my third coil in less than three years - this time a Lucas Sport model. ESM say they haven't had any bad feedback on them. There's also still a less than complely smooth pick up and acceleration - pulling on the choke doesn't mske any difference.
Ths starting problem has been the ongoing for a while but seems to be worse now. Plugs havent been changed for a couple of years or more so I've just ordered some Champion N9YCs.
simmitc
Moderator
Moderator
Posts: 4718
Joined: Thu Apr 15, 2004 9:43 am
Location: Essex
MMOC Member: Yes

Re: Exhaust clamp leak causing starting problems?

Post by simmitc »

Not running on all cylinders? Immediately check compression on all four, if only to eliminate potential head gasket problems - which could also produce an odd noise that could be mistaken for an exhaust leak.
oliver90owner
Minor Legend
Posts: 1653
Joined: Thu May 12, 2016 6:33 am
MMOC Member: No

Re: Exhaust clamp leak causing starting problems?

Post by oliver90owner »

The battery was supposedly fully charged back in April when you posted (the same problem?) and disappeared until recently?

Did you ever check for the underlying fault back then. Battery test under load. Charging circuit. I expect the problem has just reared its ugly head again and you are now asking in a different section. If the battery is not being charged properly, its life will be shortened.

Do the checks - including a compression test - and give it a service tune up. It likely deserves it. Then tell us the results.
cococola
Minor Fan
Posts: 351
Joined: Sun Apr 21, 2013 10:30 pm
Location: solihull,west midlands
MMOC Member: Yes

Re: Exhaust clamp leak causing starting problems?

Post by cococola »

Just to throw my tuppence worth in I had a similar problem with starting where my car was difficult to start or wouldn't start and I found after checking the ignition side of things and checking leads, the fault was a 3 month old Accuspark coil lead giving poor connection to the coil. I have replaced this and my car starts and runs fine.
Morris Minors..... such fun :D
barry young
Minor Friendly
Posts: 31
Joined: Mon Jun 21, 2010 2:07 pm
MMOC Member: Yes

Re: Exhaust clamp leak causing starting problems?

Post by barry young »

I've been checkingg what I can. Battery is giving 12.48v at rest and 10.98 when the starter is engaged.
The + terminal of the coil is also getting 10.98v when cranking the enbgine.
I noticed a few minutes after I'd tried all this that the coil was very hot.
Just tried holding the distributer end of the king lead near the block when cranking and there's a regular light orange spark when the end of the lead is less tham 1/2 inch from the block.

So, I'm guessing the coil has packed up again. The less than perfect pick up when accelerating would fit with that.

The car is positive earth and the + on the coil is wired to the low tension on the distributer. Can anyone confirm that this is the wrong way round? Does it make any difference? If not, why is this my third coil in less than three years? ( One standard Lucas, one NGK and one Sports Lucas) All the ht leads were new in January.

Do you think Im right?
myoldjalopy
Minor Legend
Posts: 2518
Joined: Tue Jan 29, 2013 10:32 pm
Location: Kernow
MMOC Member: Yes

Re: Exhaust clamp leak causing starting problems?

Post by myoldjalopy »

Your coil is wired up correctly for +ive earth, as the current goes to earth via the points. But I would hope for more than 12.48v..............12.6 or a bit above would be better. The spark doesn't sound great either.
Likely, although not only, culprit is the coil. As I mentioned, many modern coils have been found rather lacking in terms of reliability. Go to an autojumble or Ebay and get a good old one and swap it in. If its not the coil, you can start looking at some of the other suggestions that have been made. Did you check out the new spark plugs?
barry young
Minor Friendly
Posts: 31
Joined: Mon Jun 21, 2010 2:07 pm
MMOC Member: Yes

Re: Exhaust clamp leak causing starting problems?

Post by barry young »

Problem persisted with some spluttering and English ne not pulling cleanly when hot for a couple of days and then it cut out and wouldn't re start. I cleaned the carb bowl out of some gunge at the bottom and checked the jet was clear. Still nothing even when spraying Easy Start down the air intake. New coil- this time a made in England Remax unit. Car fired up the instantly. Time for a lengthy drive tomorrow to check it really is sorted. Forth coil in three years!
myoldjalopy
Minor Legend
Posts: 2518
Joined: Tue Jan 29, 2013 10:32 pm
Location: Kernow
MMOC Member: Yes

Re: Exhaust clamp leak causing starting problems?

Post by myoldjalopy »

Glad it seems sorted, Barry. As you know, I suspected the coil all along, given the other information you informed us of. Let us know how it goes on the test run - and if all is good now, I still suggest getting a known, good, old coil......plenty of them around.....as back-up. Like a number of replacement parts, modern coils seem to be suspect, if you take into account the number of failures reported on this forum. The old, 'proper job' coils go on for decades without issue.
Post Reply