Blue Smoke & Rough Idle - cold start diesel

Technical questions and answers about the Mazda Bongo

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Blue Smoke & Rough Idle - cold start diesel

Post by progroup » Mon Jul 11, 2011 3:07 pm

Hello Folks; yet another mystery to resolve.

I have taken time to read most prior posts given to the same subject, but not satisfied with the answers.
I believe it is time I change the glow plugs. I have a fresh new set awaiting install. I chose not to install them when I had the chance during a new head refit.

It will create a heavier than air blue cloud for about a minute or two then gradually dissipate and no further smoke even under load. Very clean exhaust after warm-up.

By the time this post is read, I may have resolved the smoke, but just in case, has anyone else had this issue with diesel Bongos?

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bigdaddycain
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Re: Blue Smoke & Rough Idle - cold start diesel

Post by bigdaddycain » Mon Jul 11, 2011 6:31 pm

I've had my glowplugs replaced as a "service item" on a bi-yearly basis (might as well, they are cheap enough) I've never experienced the blue smoke, but have occasionally experienced Black smoke after the bongo has been layed up for a long period of time (mine hibernates during the winter). Hasn't your bongo had some major engine work carried out on it of late? You may Just have some excess oil in the cylinder bores or something, i'd wait to see if the smoke clears during regular use. [-o<
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Re: Blue Smoke & Rough Idle - cold start diesel

Post by progroup » Mon Jul 11, 2011 10:38 pm

bigdaddycain wrote:I've had my glowplugs replaced as a "service item" on a bi-yearly basis (might as well, they are cheap enough) I've never experienced the blue smoke, but have occasionally experienced Black smoke after the bongo has been layed up for a long period of time (mine hibernates during the winter). Hasn't your bongo had some major engine work carried out on it of late? You may Just have some excess oil in the cylinder bores or something, i'd wait to see if the smoke clears during regular use. [-o<
Nope; all it okay now! I changed all 4 glows even though 3 were still good. Would be like changing 1 spark plug. Because I did this at 7AM; the engine was stone cold. No more blue smoke on start.

To answer your other question; I had the new glows sent to me with the new head full of anticipation, but the old glows checked out fine. I new that if trouble came around I wouldn't be waiting to get them. They appear to be fairly common and I now have 3 spares to compare a new supply with. :wink:
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Re: Blue Smoke & Rough Idle - cold start diesel

Post by M 80NGO » Tue Jul 12, 2011 8:34 pm

Just to add another angle to this smokey start up issue, i replaced my g/p's last winter and it defo made it better but since having my fuel pump off cleaned resealed timed and refitted my bongo starts like an absolute dream both hot or cold. Cold it starts first turn of the key and the auto cold start kicks in just as it should :D
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Re: Blue Smoke & Rough Idle - cold start diesel

Post by progroup » Wed Aug 03, 2011 3:57 pm

M 80NGO wrote:Just to add another angle to this smokey start up issue, i replaced my g/p's last winter and it defo made it better but since having my fuel pump off cleaned resealed timed and refitted my bongo starts like an absolute dream both hot or cold. Cold it starts first turn of the key and the auto cold start kicks in just as it should :D
A continuing saga because even after replacing the glows, voltage to the glows lasts but 1 to 2 seconds when turning the key.
After some reference to my service manual and some deductions; would replacing the glow plug replay solve this?
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Re: Blue Smoke & Rough Idle - cold start diesel

Post by missfixit70 » Wed Aug 03, 2011 4:05 pm

Sounds like a relay issue, but it could also be to do with what the ecu is telling it? the relay control is temperature dependant (based on the temp at the 2 pin sensor above the starter) once it's up & runnning, but I don't know if an issue there would affect the relay timing at start up.
Be easy enough to check the supply voltage to the switching side & see if it's that.
If it is the relay itself at fault, it is basically just a high capacity relay, it may just need contacts cleaning up internally?
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