Timing Belt Slippage:Black smoke, loud noises, low power...

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Ried363
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Joined: Thu Aug 27, 2015 11:47 am
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Vehicle: Mitsubishi Delica L300
Location: Seattle

Timing Belt Slippage:Black smoke, loud noises, low power...

Post by Ried363 »

Admin: Edited for the Technical Reference Library. Original thread is here: http://www.delica.ca/forum/viewtopic.php?f=6&t=17548

I was driving over the weekend and heard my engine instantly get louder after downshifting.

Here are the symptoms:
- low power
- black smoke on acceleration
- engine sounds more like a tractor (knocking)
- oily turbo (especially around seals)
- cannot hear whistle of turbo at light revs, only at higher speeds when releasing throttle (sounds very faint)
- possible oil consumption (time of problem: oil level was dead center of dipstick between notches; 100 miles later: oil level was 1/4 above the bottom notch on dipstick)

I was able to drive home (nearly 100 miles) without issue.

I plan to remove the turbo this week for inspection and possibly buy a new one on ebay... Any advice would be much appreciated.

Are there any other components which might have malfunctioned and caused this problem?

Also, during the removal process, is it likely that I will have to replace the intake/exhaust manifold gasket?

Thanks for any help!


Ried

1990 (92) Mitsubishi Delica l300
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Growlerbearnz
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Vehicle: Delica P25W
Location: New Zealand

Black smoke, loud noises, low power... Is my turbo bad?

Post by Growlerbearnz »

Black smoke, loud engine, low power: it's definitely a Delica ;-)

Usually turbo failure is either very gradual (a little more smoke in the exhaust, a little less boost), or very, very sudden and quite exciting. The sudden/exciting failures don't usually allow a 100 mile drive home.

If the clattery tractor noise happens at idle as well as at speed, then I'd say it sounds more like your timing belt might have slipped a tooth. Sometimes this happens because the tensioner is loose (but I'd expect it to slip more teeth on a 100 mile drive), sometimes it's because your balance belt breaks, knocks the timing belt off a tooth, and then settles into the bottom of the timing cover to sulk (until you drive over a big bump and it comes out to play again.) The oil consumption can be because of the extra pressure in the engine from the fuel being injected at the wrong time- the same thing that causes the rattly noise.

Before removing the turbo (a pig of a job), I'd remove the top timing cover and have a look around inside with a flashlight for any spare bits of balance belt. If you don't see any, turn the engine until the cam and fuel injection pump pulleys point to their respective timing marks, then look for the timing marks on the lower plastic belt cover- the crank pulley notch should be pointing at the leftmost "T" mark on the belt cover (red arrow in the picture). If any of the timing marks are misaligned you've slipped a tooth. Here's what the workshop manual* says:
11B15.JPG
11B15.JPG (190.07 KiB) Viewed 6051 times
url.jpg
url.jpg (9.21 KiB) Viewed 6243 times
(Camshaft sprocket: the timing mark on the sprocket is a little round dent over one of the teeth)
DSCF8402.jpg
DSCF8402.jpg (83.49 KiB) Viewed 6243 times
(Crankshaft pulley: Notch on the crank pulley should align with the leftmost "T" mark)
4d56 timing marks 02.jpg
4d56 timing marks 02.jpg (871.85 KiB) Viewed 6243 times
(Injection pump: Notch on the sheet metal belt deflector over one of the teeth)
*Pages 11B-14 and 15 in the "4D5 & 4G7 Engine Manual" here: http://www.delica.ca/forum/viewtopic.php?f=17&t=7335.
Nothing says "poor workmanship" more than wrinkles in the duct tape.
Ried363
Posts: 16
Joined: Thu Aug 27, 2015 11:47 am
Member's Photo Album: http://www.delica.ca/Photos/
Vehicle: Mitsubishi Delica L300
Location: Seattle

Re: Black smoke, loud noises, low power... Is my turbo bad?

Post by Ried363 »

Thank you immensely for the post about skipping teeth on the timing belt. That was the exact problem. I lined everything up,followed your instructions, and fixed the problem without trouble. You've saved me from so much stress and wasted time.
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