Cold start 2.8L Patrol running rough

Posted by Michael 10/04/2017 0 Comment(s) Q & A,

Q. I own a 1996 GQ LWB with the 2.8L turbo-diesel in it. My problem is starting in the morning. I have had the engine rebuild 3,000km ago because of a leaking head gasket, and at the same time I had the injectors and pump overhauled. I also replaced the glow plugs at the same time. 

When it starts first off in the morning, it feels like it only runs on about three or four cylinders. If it was a petrol engine, it’s like a really bad misfire. Once it has run for about 10-15 seconds, it’s running on all six. I have heard the problems with the afterglow system, and have read on some forums about changing the glowplugs to TD42, removing the afterglow buzz bar and the only problem being the glow light flashes for a few minutes. Would this be worth doing, as I’m tipping it is the glow plugs seeing how everything else has been done. 

I also want to build an exhaust for it, and was wanting to get your opinion on size. I see a lot of people in the mag with 3in exhausts, and I wanted to know if there were any problems in running a bigger exhaust – say 3.5in, all mandrel-bent with no mufflers. I will be making it myself. I don’t mind if it has no extra power gain, I just want to know if it will make less power and torque. 

A. This could be one area for sure. I might recommend you get the glow system correctly checked first to be sure that this is the real cause. Check the time the relays supply power and that the amount of time it supplies power is in sync with the Glow plug light. If it’s questionable then certainly reverting back to a manual system with a button as a last resort is fine. On a side note make sure that the correct thickness head gasket was used when it was rebuilt otherwise the initial compression hit may be not as sharp as it should be leading to cold starting issues after a rebuild also. Also make sure the pump timing is correct or a few degrees advanced as this can also be an issue with the 2.8’s.
On the exhaust I have not surprisingly seen any difference on our dyno between a 2 ½” or 3” exhaust on a 2.8 so my guess is that 3 ½” may be slightly too big and very possibly may inhibit low down response but this is just a suggestion.

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