Recommissioning Problems

[RobinTR]

My TR4A has been more or less laid up for over 17 years (only sporadic use totalling 800 miles in that time). Problem had been coolant loss, presumed via Fo8 gaskets, and family commitments which vied for attention.

 

Its first trip out, (after fitting new liners/pistons, refurbished head and new stainless steel tubular exhaust manifold), was for its MOT. There were no issues (other than front side lights not working - cured in the test by tweaking the spade connector at the fuse box).

 

Second trip was three miles to the September Windsor Forest area Register meeting... problems surfaced when someone asked who has the red 4A... as it has some liquids pooling underneath. Duly inspected, but nothing showing at any obvious leakage points, although a really strong smell of petrol once back in its garage, made me think that a likely cause lay within the carburetor bowls. A set of new SU StayUp floats and Viton tipped needle valves seemed to have solved that problem.

 

Third trip was another three mile drive, then a stop for ten minutes; after which the engine refused to start. Allowing the engine to cool (carburetors still on the list of suspects), had no effect and the repeated cranking lead to the aged battery weakening in its resolve and the inevitable call to the recovery service.

 

Back at home, access to tools quickly determined that it was the ignition coil which had failed. A prompt trip to Moss for a replacement brought immediate success as the engine fired up immediately.

 

Questions:

 

1) Assuming that it was the case that the old float valves had been leaking and thereby allowed the carburetor bowls to overfill, then how would this have lead to the observed leak and strong smell of petrol? Would this have been out via the butterfly spindles, or is it more likely that the liquids came from an entirely different source, such as an unnoticed weeping hose joint (none spotted, but all nipped-up just in case).

 

Could the "petrol" smell have been from an excessively rich mixture leading to unburnt hydrocarbons remaining in the exhaust system?

 

2) Is it common for ignition coils to fail catastrophically like this? A quick search on the internet suggests that coil failure is often associated with back-firing or other running issues, but the car had been driven for so little mileage after recommissioning that I had not had time to notice these symptoms if present.

 

Is the long lay-up likely to have contributed to the failure of the coil and if so, can anyone explain the failure mechanism? I would have expected that long exposure to engine heat would be more problematic, for example; as experienced on a long summer journey; but maybe that is not so?

 

Are failure rates so high that it would be sensible to always carry a spare coil (as well as the associated points and condenser)?

[ctc77965o]

Hi Robin,

1) Fuel Leak: What type of fuel pump do you have? If its the original mechanical then there is a chance that this is the cause of pooling fuel under the car. A leak in the vicinity of the pump (low down) will cause fuel to drain from the tank.A leak in the carbs themselves will show when the car/pump is running but will naturally stop when the ignition is off as the carbs are quite high relative to fuel in tank (on level ground). As part of your recommission I hope you replaced the rubber sections on the fuel supply, pipe by the tank, pipes by the pump and the pump diaphragm.

2) Coil: Agree they normally fail under operating and heat stress...old ones laying around seem to work for years. Again, as part of recommission you should change plugs/points/condenser/rotor/coil/HTLeads...but take care to get quality parts from safe sources as some craptastic new parts are actually worse than those originals. Are you sure the coil is dead? Could it be a low tension electrical fault in a wire/connector there?

 

I would definitely carry coil, condensor, points & rotor as spares along with a few bulbs, some wire & spade connectors. Once you've gone through some infant failures the car will be reliable for years...just an annual tweak of points gap will be required...

[peter clarke]

Starting up after a long lay up can result in leaking petrol/water hose as they harden over time. the coil is probably a one off they very rarely fail unless you have one with the wrong resistance value. I recommend that you give the braking system a really good checkover as any moisture in the fluid could have caused pitting in the master and rear cylinders and to the disc brake pistons. same goes for clutch system. Check your tyres as well as not recommended to drive on tyres more than 6 years old..... might look ok but can delaminate when they heat up on a good run.

[RogerH]

Hi Robin,

if for some reason the carbs receive too much fuel then the excess is dumped overboard from the little vent in the top of the float chamber lid. Normally the float valve is such that ot will stop the flow form the pump. If the valve fails then it will overflow.

The new needle valves are good. Grose jets are often recommended but there have been some poor ones out there.

 

Coils fail. Always have a spare handy. The rally boys often have the spare bolted in place so they simply swap the leads over.

The 'Lucas' gold sports coil has had some bad press lately. I have two from the 90's and they work OK.

Points, rotor arm, capacitor need to be kept as spares also.

 

Long lay-up and failure - many electronic/electrical do not like not being used. You get corrosion on contact faces etc.

Off topic - transistors can actually grow whiskers inside their little boxes and short out (usually the AF series)

Many coils ate oil cooled - it could be the oil settled and left some windings exposed - no cooling, over heat - pop.

 

Roger

[stuart]

In short now you have it running OK change the tyres and then drive it like you stole it! Inaction really doesnt help especially with the current fuels that go off very quickly.

Stuart.

[RobinTR]

Thanks guys for all your useful comments and suggestions.

 

Fuel pump was rebuilt by Dave Davies... did a wonderful job; highly recommended. Stands to reason that there are vents in the float bowl tops... just never noticed them; I assume they are behind the small metal plates just below the pipe connection?

 

Other re-commissioning fuel related actions had included changing all flexible fuel lines. Mine, from when I bought the car in 1978, were translucent (Tygon?) tube... had lasted really well and only now beginning to loose some of their flexibility. Replacements were cut from standard off-the-shelf SAE J30 R6 fuel hose, so I plan to upgrade to something more ethanol resistant in the near future. One problem fuel wise was the need to drain the tank of the old petrol... took out 3-4 fuel can's worth before topping up with fresh.

 

Plugs, points and condenser are all new. I tested the coil at the roadside... found a weak spark from the HV when the points were flicked while off-cam. However, nothing showing on my inline spark tester once back home. Big difference when I fitted the new coil (Intermotor Sports Coil)... are there proven better options?

 

Recommissioning included new Brake & Clutch master and slave cylinders... plus full flush through with new brake fluid. I plan to refurbish the old master cylinders etc. so had bought replacement seals from Moss or Rimmers... something for a winter afternoon, but I am not convinced about the quality of currently available rubber items, so any recommendations for alternative suppliers for these seals?

 

Incidentally, I found the clutch brake fluid to have turned a horrible grey colour... I assumed that this was due to contamination by leaky engine oil getting in via the slave cylinder, but is this the case?

 

Replacing all five tyres was not something that I had anticipated; all have good tread as you can imagine given the lack of use... the car is on wire wheels so I assume that the old tubes should also be replaced (they must be 40 if not 50 years old)? .

 

Any recommendations for a tyre of choice which would offer a reasonable compromise between cost and quality/performance? I do not expect to do a lot of high speed driving, but would like to stop and go round corners reasonably well! Also any suggested supplier in the South East who has the right adaptors to give reliable balancing of the wires?

 

Next up for action is to investigate a clonking which seems to be coming from the general direction of the the driver's foot well. Current suspects include the exhaust hitting the chassis, or worn bushes etc. in the front suspension.

 

 

[RogerH]

Hi Robin,

the fluid in my brake MC always stays clear(ish). However no matter what I do the clutch MC is always dirty/murky.

 

As for tyre choice look at this thread http://www.tr-register.co.uk/forums/index.php?/topic/59557-v-or-h-rated-tyres/

 

Roger

[stillp]

My clutch fluid is also discoloured, but yours can't have engine oil getting in!

 

Pete

[stuart]

For a coil then these are good http://www.demon-tweeks.co.uk/motorsport/ignition-coils/aldon-automotive-flame-thrower-ignition-coils

Stuart.

[stuartmac]

my clutch fluid is also always murky - why is that?

[stuart]

my clutch fluid is also always murky - why is that?

If you think about it that system gets much more work than the brake system that hardly moves any fluid at all. Its due to the rubber working against the ally of the cylinder all the time.If you polish ally your polishing cloth goes black too.

Stuart.

[Lebro]

Ahhhhhh I see.

 

Bob.

[RogerH]

AaaaaaaaaaH. I also see.

 

Thanks Stuart. I thought it had something to do with the Ali but didn't consider the frequent operation doing it.

I shall not bother cleaning it so regularly then. Another weekly job gotten rid of.

 

 

Roger

[stillp]

Very good Stuart, thanks. I've been wondering about that since 1989...!

 

Pete

[RogerH]

...so a repaired Clutch MC with a stainless sleeve will keep the fluid clean......

 

Roger

[stuart]

...so a repaired Clutch MC with a stainless sleeve will keep the fluid clean......

 

Roger

Not necessarily but maybe a better chance.

Stuart.