| Author | Message | ||
     Robert Gardner Experienced User Username: bobg Post Number: 32 Registered: 12-2012 |
Just got my car back from shop, runs good, not quite as smooth as I would like though, very slight vibration (not what it went in for) First time I have driven the car in 18 months My problem is that the car does not always fire right up as i believe it should. Acts as though the battery is low, but battery is very good condition. Starter ? Starter Relay? etc ? LRA13020 | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1626 Registered: 6-2006 |
Check that the engine earths are good (jump lead from the engine block to the bonnet catch). If you have the Lucas starter motor, it is probably on it's way out. Change for a new reduction gear type starter. Twice the speed for half the amps.  | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1393 Registered: 5-2012 |
Robert They can be found here: http://www.britishstarters.com/RR_Bentley.html I fitted one myself. I bought it after several recommendations on this forum. It has worked perfectly. Geoff | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1394 Registered: 5-2012 |
Before doing so, check that the main power cable where it bolts to the starter motor terminal is clean. Over the years, oil and gunge can collect around the connection causing electrical leakage on cranking. | ||
| Robert Gardner Experienced User Username: bobg Post Number: 33 Registered: 12-2012 |
Do the engine earths look like grey cloth? Left side looks ok, right side looks dry and almost brittle, if I'm looking at the correct things of course. Will check the starter connections when the car cools down | ||
| Larry Kavanagh Experienced User Username: shadow_11 Post Number: 12 Registered: 5-2016 |
Hi Robert, I had the same problem recently. Sometimes the starter would work fine, other times it turned slowly or just clicked. I cleaned the terminals on the short wire between the solenoid and starter and that worked but only for a short while as the problem re-emerged after a couple of days. I then removed and cleaned the earth terminals from the engine to the chassis but that only worked for a short while too. As I was about to remove the starter motor I went to the trunk/boot to disconnect the battery when I noticed that the earth lead from the battery to the body was warm so I removed the butterfly nut that is screwed into the body inside the boot/trunk and cleaned the terminal with electrical contact cleaner, that worked but only for a short while. Finally I narrowed the problem down to the isolator switch on the battery earth lead, this switch felt stiff and I noticed that after trying to start the engine this lead was warm as far as the isolator switch but cool from the isolator switch to the body. I did a voltage test with the switch turned on and found nearly 13 volts on the battery side of the switch but a much lower voltage between the switch and the car body. I replaced the isolator switch with an aftermarket one and the starter is working fine again, I believe it is spinning faster that it had been for a long time. So far (approx. 2 weeks) it's still working well. Finding that fault has saved me the trouble of removing the starter motor. Maybe you have a similar issue, these isolator switches are known to give trouble when they get older. Worth checking. Good luck, Larry. | ||
| Larry Kavanagh Experienced User Username: shadow_11 Post Number: 13 Registered: 5-2016 |
If the slight vibration is happening while you're driving it could have any number of causes but, since you said that your car had been parked for 18 months, it's possible that your tyres may have developed flat spots from the weight of the car pressing down on the area of the tyre that had been in contact with the ground while the car was standing for such a long duration in the one position. If you temporarily pump the tyres up to about 40psi and go for a short drive on a smooth road and you notice that the vibration has reduced it's probably flat spots. If you think that it could be flat spots I'm told that this problem can be partially cured by pumping the tyres to about 40/45 psi and placing the wheels in a spray booth oven for a few hours but I haven't personally tried that and, for safety reasons, I'm not recommending that you do it, Regards, Larry. | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 482 Registered: 4-2016 |
My car also has another heavy duty earth lead going directly from a starter bolt mount to the body. No one sees this, but it truely ensures the power train is fully and correctly earthed. The one on my car is a pre made heavy duty battery lead with soldered fittings. This is Available from aany good parts outlet. Mine is like this except it is black.  | ||
| Robert Gardner Experienced User Username: bobg Post Number: 34 Registered: 12-2012 |
Thank you gentleman, Larry, I don't have an isolation switch on the earth cable, always just disconnected the battery using just the wing nut when car was sitting idle for any period of time but I will check all the other connections you mentioned. Agree totally with the flat spots on the tires, was thinking the same thing, which is sad really because the tires have less than 100 miles on them When we pulled the car out of the garage, the garage floor paint beneath the tires came with it !! | ||
| Larry Kavanagh Experienced User Username: shadow_11 Post Number: 14 Registered: 5-2016 |
Robert, If an earth is bad it usually feels warm to the touch after trying to start the engine, that's a handy but not always infallible way of checking the earth connections. Shame about the tires, I'm in the same boat but at least mine are nearly due to be replaced anyway. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1395 Registered: 5-2012 |
There is another part of the starter motor circuit where a high resistance can cause slow cranking. It is in the actual solenoid that is located on the top of the body of starter motor. Under the bakelite end cover of the solenoid are some heavy duty brass connectors that can become plastered with gunge over the years. Here is a picture of the ones on my car:  When the solenoid is energized the brass plate (blue arrows) is thrown against the two connectors (red arrows). This is the part of the solenoid that switches through the high amperage current when the engine is cranked. It is worth pulling off the solenoid end cover and cleaning up these terminals before replacing the starter motor. It's possible this is the cause of the slow cranking. Geoff | ||
| David Gore Moderator Username: david_gore Post Number: 2190 Registered: 4-2003 |
Geoff, Your last paragraph IMHO identifies the problem responsible for the slow cranking and/or failure to crank which was the problem I encountered as mentioned in another thread. The contacts highlighted with the red arrows are the ones I replaced with equivalents made from Copper flat bar intended for use as earthing rods for structural lightning protection systems. The contact area had been eroded completely. The plate highlighted with the blue arrows was pristine after 25+ years of service. |
