MQ(260) glow plugs

[Dai]

So my MQ fitted with a 2.8 turbo diesel, is a little rough at idle when starting from cold
I've read that people have fitted 4.2 glow plugs ?
Just trying to understand if mine are 12 0r 6 volt ? Or if they have a post glow system ?
Any idea where the glow plug relay(s) are located ?

[Dai]

Hi all,

Can someone explain to me how this system works?

I have 2 sets of 3 plugs fitted to my 2.8 diesel turbo
There are 2 relays, and 2 contacts strips as show in the pics
The one relay activates all 6 glow plugs
The second relay only activates 3 of the plugs

Is it best to scrap this system, and just have 6 standard glowplugs?

All 3 plugs that have the double contact don't work, so I'm guessing they are unreliable ?!5031850319

[Yendor]

When the engine is cold relay 1 is switched on and supplies 12 volts to the long busbar that connects all 6 glow plugs.

3 of the glow plugs are earthed via the engine. The other 3 glow plugs (double contacts ones) are earth via relay 2.

When the glow plug control module determines it's time to turn on the after glow (post glow) It will turn relay 1 off and turn relay 2 on. This supplies 12 volts to the small busbar. Now the two lots of glow plugs are in series so 6 volts is dropped across each lot allowing them to run at around half the temperature.

To test the double contact glow plugs you need to measure the resistance between the 2 contacts. There should be an open circuit to the body of the glow plug.

[Dai]

Cheers.... That's starting to make some sense now !
Would you recommend ditching the post glow system and converting to 4.2 plugs like others have done ?

[Yendor]

If your old glow plugs are faulty it will work out cheaper to change them over to the 4.2 ones.

Have you tested your old glow plugs? Have you checked the glow plug electrical circuit?. I take it you are having starting issues?. If your old glow plug circuit is working correctly and the glow plugs are heating up fitting the 4.2 glow plugs won't solve your starting problem. How's your injector pump and injectors?, engine compression?, battery condition?, is the starter motor cranking the engine fast enough?

If you do convert to the 4.2 ones you will loose the after glow function unless you also fit a universal glow plug timer. There are a few on Ebay.

Or you could still just fit the momentary switch in the dash. Then you could manually push the button before starting the vehicle and if needed you could push it again once the engine was running.

[Dai]

I check the 3 standard contact plugs by putting them across the battery, one of them was dead, one didn't heat up quickly.
One of the double contact plugs was dead too.

Bought some 4.2 plugs, fitted them tonight , but the engine was still warm. Will have to see how it starts in the morning
I've disconnect the second relay, the first relay gives the plugs 12v for about 6 seconds.
So as usual say I dont have the after glow, and the glow plug light flashes for a few minutes ?

Hopefully no clouds of smoke in the morning !

[Yendor]

Hopefully they stay on longer then 6 seconds when the engine is cold.

If there not staying on long enough you might need to look at installing the manual switch in the dash. You only need a momentary push switch and some wire to do this. You can still use the original relay.

The glow plug light flashing is just telling you that there is a problem with the after-glow, because it's disconnected. It will keep flashing until the engine temperature heats up to a certain temperature or you drive the vehicle above a certain speed.

[Dai]

Hopefully they stay on longer then 6 seconds when the engine is cold.

If there not staying on long enough you might need to look at installing the manual switch in the dash. You only need a momentary push switch and some wire to do this. You can still use the original relay.

The glow plug light flashing is just telling you that there is a problem with the after-glow, because it's disconnected. It will keep flashing until the engine temperature heats up to a certain temperature or you drive the vehicle above a certain speed.

Started great... But then ran rough as the glow plugs had gone out
I don't want to fit a manual switch if I can help it, will either replace the 1st relay with a timed relay, or see if I can use the second relay to operate the glow plugs until the engine has warmed

[Dai]

Can seem to use the second relay, does anyone know where the glowplug control unit is located ?

[Yendor]

You should be able to use the second relay. You will need to cut the large black wire (earth) at the second relay and tape both ends up. Then just connect the other wire that was connected to the short busbar onto the long busbar at the glow plugs.

I think the glow plug warning light will still flash during after glow.

Not sure where the glow plug ECU is. Have a look in the drivers side kick panel or on the firewall below the glovebox.

[Dai]

I tried removing the earth, but no luck, I think either the relay or the control unit is faulty
I'm going to junk the second relay, and the control unit
Have ordered a timer relay that is adjustable, going to fit this where the control unit is.
Should be able to use this to control the original primary glow plug relay, and operate the glow plug light for the duration that the timer is set for
It starts perfectly now, no smoke !
Found the control unit, it is under the steering column on my model.... Just need to figure out which wire is which now !

[Yendor]

This is the wiring diagram for the RD28T that was in the Y60. We didn't get the MQ with the RD28T over here.

I'm not sure if this wiring diagram is correct for your vehicle you will need to confirm. Hopefully it will help you.

Yes just wire up your timer to switch the original glow plug relay.

[Dai]

Cheers, will take a look and see if the wiring matches the wiring on the plug of the control unit
It does seem the MQ with the RD28t is quite rare, the only service manual I've found is in Spanish !

[Dai]

Nightmare, it's been working great for a couple of week, and just the last couple of days back to clouds of smoke and not starting on the first crank
I guess some of the glow plugs have died , if that's not bad enough .... I can't get the old ones out
Has anyone else had this problem after fitting 4.2 plugs into a 2.8 ?
They unscrew all the way out the thread, but just can't pull them out !!!

[Dai]

Sorted... I had to make a slide hammer with a M4 thread to screw on to the glow plug terminal to get them out !
Worked though !
The end of the glowplug was like a balloon . I think I've over heated them by holding the button on after the engine had started
Put in new plugs and she runs again !
Maybe we do need the post glow in the UK , cause if I only hold the button on for 10 seconds then crank and release the button , she starts but then runs rough for a minute or two
It it's quite cold here !

[Dai]

Has anyone fitted the Bogaard Glow plug controllers ? They appear to only be available in Australia, I cant find a UK supplier
I believe you can set a post glow to pulse the glowplugs , that way I can use the 4.2 Plugs with out burning them out !
Post glow is definitely required in UK winter temperatures !

[cos]

I have the same engine and I think the original sistem must keept working especialy for postglow feature . Most common malfunctions is from a burnt contact points or burnt flexible wire inside relays ( big black one , double switch for postglow , and not so big black simple switch relay for rapid 6 seconds preglow ) . Is not dificult to fix using a similar flexible wire from carbon brush ( found in electric starters ) , or using some another relays for glowplugs ( same relays is in similar motor in Patrol Y60 , easy to find at wrekers , only a diferent metal braket and diferent place under the hood - next to the batery under the metal lid ) or some ordinary relays found in any diesel engine car .
The sistem is simple , a temperature sensor in engine head , a control unit who rarely cause problems and the two relays - nothing to be scared about . The corect glowplugs is NGK CZ51 6,5V ( 1+2+3 cil electric conected alt threaded body and M4 terminal ) , NGK CX 51 6,5V , with insulated body , electric conected at M4 and small insulated plateau .

Most common mistakes is wrong check glowplus , wrong glowplug instal especialy at 4+5+6 cil without insulation spacers , wrong glowplugs . Most common defects is burnt glowplugs ( only preglow feature work , with 12V direct feed at all glowplugs ) , postglow not working because glowplugs supose to be in serial - 4+5+6 pozitive feed in serial with 1+2+3 ... if one or more glowplugs is not OK , postglow will not work ) .

[MATIJA0707]

I have also problem with glow, and i find that my 3 cylinder and 4, 5 cylinder is not working glow plug.

Result is no heating at all, car is not stariting and heating lamp in cabine is blinking.

[MATIJA0707]

Patrol is 2.8 TD RD28T 1991.g

[MATIJA0707]

I hope when i put new glow plugs will work.

[cos]

Check relays too .

[GabrielMk3]

I had triple up the problems. Several lads complained because of lots of white smoke on startup and only a couple of cylinders working until the engine got warm. Well, I had 4 cylinders working, the glowplug lamp was blinking, and lots of white smoke. Turned out to be both bad plugs, bad wiring on the rails AND a loose/full oxide.

So, check all your contacts - are they lose/oxidized? Are the relays jumping around not being fastened?
Check your glowplugs and the rails.

It should not be too difficult to spot the problem!

[meakinelli]

thanks for the info, going to try mine asap. have got the push button but never tried puching it once the buggerr was running. will see

[meakinelli]

Started great... But then ran rough as the glow plugs had gone out
I don't want to fit a manual switch if I can help it, will either replace the 1st relay with a timed relay, or see if I can use the second relay to operate the glow plugs until the engine has warmed

how did it end up? did the white start smoke issue clear up with the new glow plugs after your latest mod? I have the dash board switch fitted so i just press and hold that for a bit. I get lots of white smoke, which then clears up after a minute or so. i hold the switch on after starting although i didnt really see much difference. maybe i should change the plugs. What are the 4.3 you spoke about? Meakinelli