Any one got step by step instructions on a hot start relay?

[Jakep]

Hi,

I’m having issues starting my bus when she’s warm.

Been told to fit a hot start relay,

Does anyone have a list of items needed to do this job and then a step by step guide on how to fit it all please?

Thank you

 

[mike202]

If you do a search on here there’s quite a bit of useful info about this.
The popular diagram I used is this one:

 

[AlanWesty]

Not sure how that will help with the hot starting isssue, but accept that the continous cranking will heat up the switch and could wear it out.
If there is another explanation of why to fit the relay I'm keen to learn.
BTW, also just fitted a relay today just in case, don't want to start searching for a new switch.

 

[mike202]

It just makes the current travel a shorter distance straight to the starter instead of all the way up to the starter switch and back again. Because of the distance there will be some voltage drop, more if your wiring is old.
With the relay only a small current goes through the starter switch just to activate the relay

 

[static]

I have one. It does help it start, but it has absolutely no effect on a hot start.

 

[ozziedog]

All the things said above ^^^ by Mike and Static plus fifty years of that current going through those connections gradually takes its toll on the wiring as it enters the terminals and every single thing in the switches.
With your hot start issue, have a careful listen to the speed that your engine turns over. If it turns over nicely when cold, then starts, try and gauge the sound of it and think to yourself about how fast it is turning over. When you initially go to start it listen to how fast again you think that it’s turning over. If it is noticeably faster when hot, I’d have a double check of your valve/ tappet clearances. As everything expands when hotter, if your clearances are a little tight, when hot that tight may lead to them being slightly open and enough to loose that vital bit of compression needed to start it up. I’ve got a relay fitted, moreso to relieve the other components than to help hot starting.

Ozziedog,,,,,,,,, just some thoughts.

 

[mike202]

It’s also sometimes called a ‘hard start relay’ modification. That is: it makes starting easier with the relay.
Maybe the word hot is used as when everything has warmed up on a hot day driving and you crank the engine to re-start at the petrol station/ tea stop etc, the wires to the ignition switch will be warm/hot and so less conductive than when you set off from home when everything was cooler. This causes the voltage to drop even more. When I first put mine in I didn’t have any problems re-starting the engine. I did the mod any way to stop the starter from having to deal with all that current.

 

[Earlybay1]

Check the basics. Make sure all earths are good to chassis and the braid from engine to chassis with no visible corrosion. Remove clean and coat connections in vaseline or copperslip. The copper braid which is attached to gearbox often will have corrosion because of dissimilar metals of copper braid/solder and aluminium gearbox connection. Check the starter connections including the solenoid soldered joints from the start switch spade terminal. Starters are often forgotten about and possibly have been on the bus since new without any checks.

 

[Jakep]

All the things said above ^^^ by Mike and Static plus fifty years of that current going through those connections gradually takes its toll on the wiring as it enters the terminals and every single thing in the switches.
With your hot start issue, have a careful listen to the speed that your engine turns over. If it turns over nicely when cold, then starts, try and gauge the sound of it and think to yourself about how fast it is turning over. When you initially go to start it listen to how fast again you think that it’s turning over. If it is noticeably faster when hot, I’d have a double check of your valve/ tappet clearances. As everything expands when hotter, if your clearances are a little tight, when hot that tight may lead to them being slightly open and enough to loose that vital bit of compression needed to start it up. I’ve got a relay fitted, moreso to relieve the other components than to help hot starting.

Ozziedog,,,,,,,,, just some thoughts.

Thank you! I did the tappets on Saturday and they were far too tight!

Reset them all to 0.15 and now running smoother and a lot cooler!

 

[Jakep]

Thank you everyone!