Hi,

I have a 87 300DT with just over 200K. The problem with it, is starting.
After been stopped overnight, it will not start. When I crank the ignition
key, it looks like wants to start, but doesn't. If I am lucky, it eventually
starts. Another times it will not. I replaced the preglow relay, and the
problem didn't go away.

1) Should I replace the glow plugs? Because I don't have a meter to
measure the current without spelliting the wires, I have not tested the
wires and the plugs. I will get one today. However, the resistance of
the glow plugs #'s 1, 2, 4, 5 and 6 is 0.9 Ohms. I couldn't reach #3.

2) Can it be the temperature sensor? Yesterday, it was a warm day. The
car started at the third time I cranked the engine. I stopped the car
and 5 hours later, it started first time. This morning, it is much colder
here, I had no luck.

3) In another posts here, other owners mentioned having problems when
the injectors pump leaks. I see a leak on top of the injectors pump.
Could it be the cause?

4) Yesterday, I measured the voltage from the starter wire to the preglow
relay. When I cranked the engine, I measured 5 volts and while cranking,
the voltage went to ZERO. Is this normal? If not, what could be wrong?

TiA,
Demi

Just to satisfy my curiosity, please connect a voltmeter to one of the plugs and turn the key to the #2 position. Please confirm that you have 12V at the plugs for about 40 seconds after you turn the key to the #2 position.

Hi Brian,

I just measured the voltage, as you asked. Both #'s 1 and 6 have no
voltage. Actually, it is about 0.0007 and 0.0009 volts. What does it
mean, apart no current reaching the glow plugs? Bad glow plugs? Bad
relay? Bad wires?

Thanks,
Demetrio

Well, you have found your starting problem, that is for sure.

First question: Do you have voltage on the other four plugs? 12V?

If yes, it's time to check some wiring.

Remove the plug at the glow plug relay that sends voltage to the plugs. There will be six sockets in the plug.

Use your meter and check for continuity between each of these six sockets and the respective glow plug. I would expect that you will find continuity on each of them, but you never know.

If you have proper continuity of the wiring, the only thing that remains is the relay.

Used relay? Warrantee?

Demi,

Remove and insert the GP connector from the GP 10 relay times. Then check the voltage at all the GP.

Also, when you measure the resistance of the GP, you should do it thru the holes in the GP cable connector after it is removed from the GP relay. This removes any parallel resistances that will give you incorrect redings.

P E H

I was contemplating the advice from PEH and I concur with it.

It would be highly unlikely for the GP relay to function properly for four glow plugs while providing no voltage to the remaining two.

Additionally, you have installed a second relay with identical results.

This points to a potential problem in the connector at the GP relay.

You may not get continuity on the two plugs that you previously measured with zero voltage. Take a careful look at the sockets on the plug. Determine if there is any corrosion in those sockets prior to proceeding.