GQ smoking problem

I bought a GQ 4.2 diesel about 3 years ago. Has an aftermarket turbo. It had a leaking injector pump but it was never enough to worry about.
Recently I had the injector pump rebuilt by Sheppards Diesel and now it smokes when started.
It's a white/blue smoke and when started cold, the engine coughs for about a minute while smoking. After that it seems fine and stops smoking.
But if it sits for more than an hour or so, then the engine cools down enough and it smokes again on starting.
Didn't smoke when starting until the injector pump was rebuilt.
Any suggestions?

I would be looking at glow plugs as the white smoke is indicative of a colder combustion however blue is oil. The blue might however be a shadowing effect from the white.

I've never changed glow plugs before. Is it an easy repair?

Yes, screw out old ones, screw in new ones, bit fiddly, glowplugs can be difficult to remove due to age, download a copy of the manual on this site and have a read, I am sure there are test sequences you can run to confirm if its glow plugs or timer also.

I'll check it out, thanks

I went to the manuals page. Do I need to log in anywhere to access them?

Hey mate sounds like a bit of a coincidence that happened same time as injector pump was rebuilt, however definatly worth trouble shooting glow plugs then should either fix it or rule them out. Can test them by putting power to them, should glow red fairly quickly. Can also put a multi meter across them and check resistance think it should be round 1ohm from memory but should be in the manual hopefully.

I have been trying to troubleshoot same issue in mine for a while now still to no avail que frustrating. Have put new glow plugs in recently only to find a couple faulty, however still not starting well in the cold will re test them and take it from there.

Also check the hand primer is firm before starting could have a small air leak somewhere something worth checking anyway. If all still no good maybe give the place that did the injector pump a call see what they reckon.

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Hey Rossco, Yeah, took it back to Sheppards a week after they did the injector pump and they had the car for a few days trying to eliminate as much as possible. They even hooked up a separate fuel source to eliminate my fuel, lines, etc. They couldn't find out why it was doing it. Don't recall them saying they checked the glow plugs though, so here's hoping that might be the problem.
Primer is as hard as a rock. That was something else I was showing them. But when they disconnected the fuel line, it was easy to pump, so that side of it is ok.

I would also check the glow plugs remain 'on' for the required time. They should stay on for a short period after the engine starts when cold to assist with keeping the combustion zone - cylinder hot, then go off. Check this timer function as well as the voltages.