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MG TD TF 1500 - Diagnostic analyzation

I have a 5mi round trip path that I take for test driving (in case I have to push it home). Two weeks ago it ran fine for first 5mi but then at about mile 8 she started running like on only 1/2 cyls. Would roll along as long as I didn't give throttle if I did it woul want to die and as I let off throttle she would back fire. OK so I then fitted new cap & rotor, plug wires. and plugs. Ran fine for first 5mi then did same thing at about mile 8. Won't take any throttle and when I let off throttle she back fires. Any ideas where to start. Greg & Grimm
G.J. Cenzer

Are you sure it's the ignition?
It could also be fuel starvation.
Ignition-coils are known to fail when warming-up but a five mile run may be to short for that.
Willem van der Veer

If I turn the jet adjusting nut all the way up, then what is a good guess for the number of flats to turn it back down as a starting point for carb adjustments. Seems to me I remember 12 as being a good number to start with. I know that I'm getting some air leakage at the throttle shafts but I was hoping I could wait and do the re-building this fall after the Battle of the Brits Bike/Car show. The backfiring is sorta what puzzles me. Greg & Grimm
G.J. Cenzer

G&G
Unscrew the jets six flats down as a starter. (One full turn) The mixture will normally be too weak at this setting. A couple more flats down will get you very close to an ideal mixture if the needles are correctly located.
John
John James

I ran into an identical problem that occured from time to time and then would go away. It turned out to be the distributor condenser. When I restored the car I did my initial test runs with the original condenser with the intentions of replacing it. I never got around to it as I never had a problem. Once the condenser started to fail the car exhibited the same characteristics as you describe when it heated up, even on cold days. Solved the problem by replacing the part. Cheap fix compared to most.

Good luck
Dick McCutcheon
Safety Fast
Dick McCutcheon

Something electrical heats up as above (coil/condensor), or restricted or no fuel. When it starts popping, you can stop and remove the float bowl lids and see if they are mostly full of gas (carefully so don't splash on hot manifold). Also check for carb/manifold air leak, but bet ignition.
George Butz

Well folk's like I said I wanted to wait till fall after the Battle of the Brits local bike/car gathering (last year I rode my '65 BSA 500/w650 top end) but I dove in head first today and rebuilt the forward carb. It's a miracle the car even ran cold. Carbs are a disaster. Don't even have proper gaskets in the jet area and float bowl attachment. Float bowels are a joke full of rust and white residue (in alunimum bowl). The little filter screens at the banjo connecton you couldn't even see day light thru them, you can see lots of day light now and the brass shines like hardware on a ship (that's where I learned how to shine brass many years ago). I'm also gonna bite the bullit and install the new points and condenser that I have. You know that when you get older you forget some of the ideoligies of your youth but it's coming back to me now. When I was back in my early TD days I used to preach that one of the beauties of these machines was that if you gave them proper love and attention they would never fail you. I used to drive to Chicago once a month back in 1956-57 without I94 (wasn't completed yet) in my first TD and never had a problem because I would give her tender loving care. After every trip I would check out everything just like the driver's hand book said, by buddies said yer nuts. Antways I digressing here so I will let all know how it works out in couple days. (gotta take a KID sitting day off). Greg & Grimm
G.J. Cenzer

Greg - "...brass shines like hardware on a ship (that's where I learned how to shine brass many years ago)". Good old Navy philosophy - "work it may, shine it must" it sure kept those ships on the go. Cheers - Dave
David DuBois

I had almost the same problem when I got my car 6 or 7 years ago. The p.o. promised that the car would be running for me and drove it for a tune-up, etc. He got stuck and had to have the car towed back to the service place twice and then finally made it home, after spending about $1100 on a fuel pump, carb rebuild, etc. I picked up the car and brought it home on a trailer and everytime I took the car out it would run fine for a few miles and then I would have to push it home. I replaced the cap, rotor, points-cleaned out the tank because it felt like fuel starvation. The crazy thing was that after a few hours, it would start and run fine again for a couple of miles and the cycle would repeat itself!! I finally replaced the coil-against everyone's advice, and that did it. It is now totally reliable.
Steve Tobias

Another 2 cents....did you install new plug wires with the crap ones from Tiwan?
That has got to be some of the worst wire I have ever seen in my life! Check for "weak spark" when warm!
Lucas Bumble-Bee wire is worth the money!
Cheers,
David 55 TF1500 #7427
David Sheward

Sorry for delay. Major W-XP problems. Where do I get "Bumble-Bee" wire? Greg & Grimm
G.J. Cenzer

Well, I rebuilt the carbs, new everything including throttle plates,corks, washers, etall. Now before I did this the carbs DID NOT LEAK just thought they might be running bad and they were pretty messy inside. Now all back together with new parts from Midel in Austraila (not Taiwan) parts and the both leak when I pull the jets down for choke. When pushed up home no leak but pull down 1/16 inch and leaky away. What did I miss? Neddle valves are working because the pump stops pumping and nothing comes out of overflow. Greg & Grimm
G.J. Cenzer

Make sure an old cork/cupped washer wasn't stuck in the jet bearing (bottom half)- very hard to see and to pick out, I have run across rebuild kits that the tiny thin copper washer that fits around the lower jet housing (the piece that the adj. nut screws on to) is too thick and won't seal causing a big leak. Did you soak the corks overnite in oil? Lastly, it is really easy to get something out of order (washer/spring, etc.). Also, were the jets new? Whichever, check and make sure no fine verticle scratches or they will leak.
George Butz

OK Leaky stopped!
Last year I bought some carb rebuild stuff from Midel Pty in OZ and had no trouble. Trouble now is that the little brass jet seal washer is a stamping which means the there is no conrol over the circumference dimension plus it is of thinner material which means it will NOT properly compress the cork seal. OK now instead of trying to rework everything new that is not good I decided to use the old original brass jet seal washer as IT IS A MACHINED TURNING which means it has the proper thickness in it's corners so as to apply pressure to the cork to make a good seal. So here's what I did: on foreward carb I used new cork, new jet, and old machine turned brass washers, presto NO LEAKY NO MO! On the rearward carb I used the stamped brass washers new jets and "O-RINGS" that's right "O-RINGS". I got this box of O-rings I bought at Harbor Freight for about $4 with 3500 rings of many different sizes. I picked a size I liked the tightness feel of and used two at each end because the stamped brass washer is deeper than the machined one. Waalla NO LEAKY here either and jet operates as smooth as the front carb. These O-rings are made of NITRILE 70 SHORE, ASTM-2000, SAE J200, BUNA-N BG715. They do not appear to be affected by lacquer thinner or Bestine or Acetone, or gasoline. Can't test run till next week though because this weekend is annual family re-onion (wife's side French Canadiens) great fun people at's why I hooked up. Have a nice weekend all. Sorry I'm NOT a "dream cruise person won't be there. Greg & Grimm
G.J. Cenzer

This thread was discussed between 16/08/2004 and 19/08/2004

MG TD TF 1500 index

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