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MG TD TF 1500 - Loses power when hot

A friend of mine is working on a TF. The motor runs fine untill hot. Can't get the engine to accelerate unless you lift the pin for the dash pots. It will rev while holding the pin up and will run for a moment but will go back to virtually no power after idling for a moment and wants to stall. Unless you hold the pin up it will not accelerate. This only happens when it's hot. Engine has been rebuilt along with the carbs. Any thoughts?
Any help appreciated.
Dan H.
Dan Hanson

Shut it down when hot and carefully remove the float chamber lids and look at the gas/float level- top of float should be grossly 1/4-1/2" below rim of the bowl. Are the correct dashpot damper caps fitted- vented or not -I think not on TF? Sticky pistons- remove air cleaner and make sure they are free. Piston springs in place? Did this happen always after carbs rebuilt or just start? Major air leak? Ignition- I replaced my coil, wires, cap, rotor, refitted the points/condensor, etc. and then of course blamed Moss for bad needles. Seems the person looking up the part # (me) ordered MkII needles-oops.
George Butz

George, Thank you. Everything is new. The carbs were just rebuilt. It runs fine when cool, it just looses power when hot unless you lift the pin. Very strange. Seems obvious as a carb problem due to the pin lift as a cure. It's the "it only happens when its hot" that baffles me. We will look for the problem areas you suggest.
Thanks, Dan H.
Dan Hanson

Our local T series expert ran into a similar problem with his newly rebuilt TC. It was way down on power once it got warm and worse at higher elevations. Like George he replaced all the ignition compoments and worked his way through fuel supply. In the end he was actually wondering about a bad valve or leaking head gasket. Anyway, it turned out to be an obstructed air filter! Even these guys can be caught out by something that simple.
Tony
Tony Cove

Dan - Everything new does not automatically mean that it is all adjusted properly. The fact that you have to lift the piston in the carb with the tickler pin leads me to believe that the jets may be slightly off center, causing the needles to rub and inhibit the movement of the pistons when the engine compartement gets hot. Your friend will need to remove the air cleaners and run the car until the symptoms return, then check the pistons by trying to lift them with just his finger nail under them. Any drag whatsoever is unacceptable and can cause the symptoms you describe. Of courst this procedure will also check out Tony's idea of clogged air filters at the same time. Good luck - Dave
David DuBois

Just a thought, each carburator piston and dashpot are a matched pair. If the pistons were inadvertantly swapped during thr carb overhaul you could end up with an unusually tight fit between the piston and dashpot on one carb and a loose fit on the other. As the carb heats up and the alloy expands, a snug fit may progress to the point where the piston binds and does not raise as it should producing the symptoms you describe.

Dr.Frank
Frank Graham

For me it was the cylinder head which needed to be retight.
JM Thély

After running my barn save arounbd I was experiencing power failure after 10 -15 mins running( vehcile seemed to be fuel starved wouldn't run faster than 2500-300 RPM. The previous postings led me to believe my furure was draining and cleaning the gas tank. Just porior to this I tried the simple obvious thing I discnnected the fuel lines at each dash pot and found the screens caked, on close inspecvtion the inner surfaces of the dash pots and the floats were covered with residue and varnish. Removed dashpots cleaned everything. Now I don't have top drain and clean tank. Lesson l;earned try the easy way first
Jon L

Jon,

You might want to check the screen in the fuel pump as well, since it's only about a foot upstream of the carbs, it's likely got the same crud. If theres anything other than varnish on the screens, I would recommend finding the source.

Good luck, Evan
Evan Ford - TD 27621

This thread was discussed between 23/09/2003 and 06/10/2003

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