Warm start issue.

Hey guys I am now at a loss at trying to figure this one out so thought I would ask for some help.

I am putting this same message on several forums to try and get the widest knowledge base I can.

Ok well I fitted a BOA engine to my sapphire originally with an MT75 gearbox. Running it like this for 4 months I had absolutely no warm start problems at all. The only problem I had was a gearbox issue.

However to solve the gearbox issue I converted to using the cossie T5 box. Obviously this required a different starter motor. (This was hard enough to find as it was) I know the bendix gear is correct as I am using the same bendix from the starter I was using originally. I also know that it is not going into far when throwing as I had a spacer made up.

Well the warm start problems surfaced last summer after I changed the gearbox. However I managed with the problem and once it got to winter it was cold enough for the engine to cool down quickly so I didn’t really have much of a problem. However for the last few months since it has warmed up it has started to get really bad to the point that I have to make sure that I leave the engine to cool down for at least 30 minutes before trying to start again (causing major embarrassment when trying to start after filling up with petrol, thankfully an AA van was there to help me out)

Ok I have been trying to find the problem for the last few days. I will list what I have tried so you won’t be suggesting something I have already tried.

1. battery checked at a battery place for cranking power
2. adding an extra power lead from battery to starter motor
3. I got the starter motor refurbished, with a new solenoid etc. – no difference
4. added 2 extra earth straps, so I now have earth straps from exhaust to body, starter motor bolt to inner wing, engine to inner wing same position.
5. changing the exciter lead from ignition switch to the starter motor
6. putting a direct power feed from battery to ignition switch
7. By passing ignition switch by going from battery to a switch and then to the starter motor.

I carried out several voltage tests with the engine warm and cool to see the difference and these are the results, all the tests were whilst cranking:

1. voltage across battery– 12+ volts warm and cold
2. voltage across solenoid power in and starter motor body – 8.4v when warm 11+v when cool,
3. voltage across solenoid to starter link to starter body – 7.5/8.5v when warm 11+v when cold
4. There were 3 more tests to check the voltage drop insulated link, voltage drop solenoid contacts and voltage drop earth line which all should be less than 0.5v and they were.


All of these seemed to help but when the engine got warm made no difference and it still cranks over very slowly when warm.

When the engine is cold/cool it cranks perfectly fine.

Sorry for the essay but thought I would give as much info as I could. Any help I would much appreciate it as I now don’t want to drive my car when I no I wont be long between stops.

Thanks in advance

Adam