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MG TD TF 1500 - Not firing

I know (after 60+ years of working with them) I should have solved this one, but I haven't!

I replaced the exhaust manifold gasket on the TF1500 after checking the timing and getting a new loud noise from the exhaust. On dimantling around half the old gasket was missing. So far, so good.

After a struggle to replace the gasket, which needed more than a few contortions of myself and the inlet manifold (only part disconnected) it was replaced and bolted down.

Since then the engine has refused every attempt to start.

The pump clicks several times and fuel is in the carbs. I have blown the jets clear in case any sludge had entered during the contortions. The pistons fall with the correct clunk. The accelerator linkages are in place and working, as is the choke cable.

Timing and spark gap have been checked and the valve opening is OK, sparks appear at the end of the lead held against the engine block. An aklternative coil has been used which made no diffrence.

The battery is fully charged.

What have I missed?
Ian Bowers

Somehow the sparkplug leads from the dizzy got mixed up?? Just a WAG. Jud
J K Chapin

Ian,

If you have refitted the air filters, you could remove them and, with a syringe, squirt pure petrol in each carb while somebody is turning the engine over. If you get spitting and backfiring, then check for air leaks.

John

J Scragg

John beat me to it. Doesn't even need to be petrol just flammable, my neighbour used screen de-icer when I was trying to get a neighbour's petrol mower going it fired and ran for a second or two proving it was a fuel problem.

A tap on the carb(s) can sometimes be all that's required, needle and set muck or stuck.

Also firing order work checking.

If the fuel is old try fresh in the bowls.

You could also check the spark is a good spark, to all cylinders swap in a known good HT lead set.
Nigel Atkins

Ian--that first loud bang in the exhaust you heard ,was the car still running ok after that or was that the last sound it made---
William Revit

Hello, I've had a new rotor bug fail like this. Engine quit without a warning. I installed the old rotor and bingo.
Kim Herford
W K herford

Apologies for the long silence, I had to go to Finland.

Taking the points raised in order:

Firing order 1342 checked and in the right rotation
Air filters are off. CarbCleaner and WD40 sprayed in with no effect.
The engine ran correctly immediately before the exhaust manifold work was started, so the fuel worked well then
Rotor from the Distributor Doctor, changed wioth no gain.

So, still puzzled. Next to change the condensor (though that is rarely a complete block to firing).
Ian Bowers

Ian,

You mentioned above that you had a spark, In that case, we can assume that the capacitor is OK. Forget about WD40, carb. cleaner and granny's cooking oil, try good old petrol.

John
J Scragg

Hi Ian:

I concur with John about using petrol, or proper starting fluid. I've seen videos using WD-40 and carb cleaner. However, those don't really atomize that well out of the can,(or are as volatile), as a can of starting fluid would. Also...since you mentioned the difficulty in getting the new gasket installed, are you confident the manifolds are properly seated against the head and there is no air leak? I only mention that since it might be possible there is a gap underneath you cannot see, and the manifolds might be slightly cocked and thus not fully seated, yet the bolts are tight?

My two pence!

Jim
Jim Rice

Quote "
I replaced the exhaust manifold gasket on the TF1500 after checking the timing and getting a new loud noise from the exhaust."

Re-reading your first statement am I correct in understanding that it was the exhaust noise that led you to remove and change the exhaust gasket? If so the implication is that the none starting was/is caused by a failure BEFORE you changed the gasket. The fact that you have a spark as stated even if leads mixed up would mean the car would at least fire but you seem to imply that there is no combustion taking place at all. If so it would be my thoughts that either fuel was causing the problem or a mechanical failure.
With my recent incorrect assumption whilst on tour (very hot weather and hills) that I was suffering from vapour lock after changing/checking everything electrical APART from the ignition coil (no spare with me) without the problem going away it wasn't until I got home and did change the coil my problem seems (hopefully) to have been resolved. From what I now diagnose the car would run OK for about 45 minutes before backfiring/stalling started. Stationary for sometime engine ran again. Coil was I believe breaking down over time when getting hot but once cooled would fire up. Whilst on tour I was just acting like a headless chicken and just not thinking things through properly.
JK Mazgaj

Taking things in turn:

I have now sprayed the intakes with real, old fashioned, petrol. No firing.

Have again checked the timing (which is what I was doing when the failing exhaust gasket made its presence felt). The distributor is definitely set to spark to Cyl 1 at TDC and TDC confirmed by checking that both the rockers on Cyl 1 are free from the valve stem when the timning mark is aligned with the pulley. Spark order 1342.

I leave the ignition off for a period to ensure the coil is cool before attempting to start.

Using the old adage, if you think the problem is electrical first check the fuel; have done that, so now the only answer lies somewhere in the spark generation area - I think.

Off to the Lake District now and the TDII. Hopefully that will behave.
Ian Bowers

Ian, if you have spark and fuel then the only thing left is compression. Run a compression test on each cylinder. My guess is the bang you head was something breaking in the engine. 😬
John Hunter

Ian
I read this-
"Have again checked the timing (which is what I was doing when the failing exhaust gasket made its presence felt). The distributor is definitely set to spark to Cyl 1 at TDC and TDC confirmed by checking that both the rockers on Cyl 1 are free from the valve stem when the timning mark is aligned with the pulley. Spark order 1342. "

So ,when you have the timing mark on TDC No1 with No1 rockers loose , then yes No1 should be firing---
--Have you checked that the rotor button is pointing at No1 at this time and that the leads are 1342 from there in an anti clockwise direction
William Revit

Had the car been periodically back firing previously at all? Is it possible that any backfiring had caused the damage to the gasket? Again I query whether the fault occurred before the gasket discovery or after. Couple of other pointers. Continuity/damage/loose low tension lead to the distributor. Once years ago had a hairline crack in the distributor cap. Virtually invisible. Only saw it whilst trying to start the car in a dark garage. These things are so so frustrating but you will beat it.
JK Mazgaj

I see you checked for spark at the wire, and you checked plug gap but did you check plugs for shorts. Believe it for not I managed to foul all 4 plugs while working on my TD. took a couple of week to sort out. early to check with multimeter without taking plugs out, should be no reading from plug to ground, any reading will break down with high voltage and never spark.
B W Wood

As said before, I am now in the Lake District and for the next 5 weeks. Work and reports on progress will resume on return.
There has been no backfire issue.
The resistance check on the plugs has merit, though I did give them a good clean recently.

Now to enjoy the TDII which lives up here!
Ian Bowers

Well, after 3 months of checking and changing every d****d part which may be involved in firing up, tiing, fuel and electrics and signally failing to get anything more than an occasional single cylinder fire.

Today she started and ran fine.

Here's the lesson learned: I replaced the air filters, poured fuwel over them, waited 2 minutes and away she went. No trouble since.
Ian Bowers

This thread was discussed between 11/07/2022 and 29/09/2022

MG TD TF 1500 index

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