No cranking when warm

Batteries, Alternator, Wiring, Lighting, etc. (Please discuss ignition problems in the Engine category)
Post Reply
Message
Author
gary_nz
Newbie
Newbie
Posts: 5
Joined: Tue Mar 12, 2019 3:03 am

No cranking when warm

#1 Post by gary_nz » Thu Mar 28, 2019 10:51 pm

Triumph 2500TC 1976 auto - I have an issue where the engine will not crank when the engine is hot. If I leave the car to cool for half an hour or so it cranks every time without fail.
When it fails to crank there is no clicking, in fact there's no noise at all.
Ignition light is lit, transmission in park and have also tried in neutral.

Things I have tried to track this issue down... All done when engine both cold and hot.
Checked voltage at solenoid (large lug) and I get 12v when key in cranking position.
Earth cables seem fine.
The transmission selector inhibitor switch checked out okay hence getting 12v at solenoid when key in crank position.
I tried connecting a battery directly to the starter terminal and the started turned okay.
My gut feeling at this stage was that the solenoid is seizing or the pinion gear is seizing on the starter shaft. I decided to get the starter motor and solenoid looked at so I removed it and had them serviced.
The starter bushes were replaced and the armature refurbished.
A brand new solenoid was fitted.
Installed the new starter and there's no change to the situation, hence this post. I have booked the auto electrician for next week but thought I would try here to see if anyone has any tips.

Cheers,
Gary

johnnydog
Senior Member
Senior Member
Posts: 999
Joined: Tue May 14, 2013 12:33 pm
Location: Lancashire

Re: No cranking when warm

#2 Post by johnnydog » Thu Mar 28, 2019 11:45 pm

I would have gone with the inhibitor switch, but as you have eliminated it, the next thing would be the adjustment of the selector linkage. Have you tried turning the starter at the same time as moving the lever slightly from its 'P' or 'N' position? I have had autos in the past that were very temperamental in P or N when cranking, and it was due to incorrect adjustment of the linkage rod, which was in effect was causing the inhibitor to 'think' it was in another position other than P or N, and therefore wouldn't crank.
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

gary_nz
Newbie
Newbie
Posts: 5
Joined: Tue Mar 12, 2019 3:03 am

Re: No cranking when warm

#3 Post by gary_nz » Fri Mar 29, 2019 12:58 am

Thanks for the tip. I'll give it a try.

johnnydog
Senior Member
Senior Member
Posts: 999
Joined: Tue May 14, 2013 12:33 pm
Location: Lancashire

Re: No cranking when warm

#4 Post by johnnydog » Fri Mar 29, 2019 8:03 am

If I am not mistaken, the correct adjustment details are in the official workshop manual.
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

sprint95m
Senior Member
Senior Member
Posts: 136
Joined: Tue Jun 03, 2008 9:27 pm
Location: Caithness, Scotland

Hmmm.....

#5 Post by sprint95m » Fri Mar 29, 2019 11:23 am

Being a slant four Dolomite owner this is a familiar problem although on these the solenoid does usually click and the car eventually fire up.
On the Sprint I had in the 90s the starter would just stop altogether. I did fit a new original solenoid to effect a cure
but they solenoids are no longer available new and I don't have faith in the replacements (short lived).

A different solution is to employ a remote relay between starter switch and solenoid.
P6B Rovers had this from new and Tony Hart does this alteration on Stags too.
The problem is excessive heat from the exhaust.

A heat shield could also be a solution?



Please do inform us of how you get on.


Ian.
Owner of a 1979 Dolomite Sprint (EFI),
previously ran for nine years a Dolomite (1850), a 2500S (for 4 years), a Dolomite 1500HL (for a few months),
a Dolomite Sprint (for 10 years) and a second 2500S (for 5 years until 2007).

gary_nz
Newbie
Newbie
Posts: 5
Joined: Tue Mar 12, 2019 3:03 am

Re: No cranking when warm

#6 Post by gary_nz » Fri Aug 30, 2019 5:37 am

I finally got this sorted. I installed another starter and the same problem occurred.
I decided to bypass the inhibitor and that is the issue. The inhibitor must be adjusted very close to its threshold and when warm it exceeds the threshold limit.
It's a pity I did not try that in the first place. I did not have the Haynes manual at that stage but got one recently and saw it was relatively easy to bypass.
My test of voltage at the starter must have been flawed which led me to believe the inhibitor was okay.
Thank you to all who read and provided suggestions for this issue.

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests