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Old 24-03-2013, 19:10   #1
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Yanmar 4JH HTE - Remove Turbo

Hi

I have been following this site for some time and learnt so much. Thank you
CF members.

The current engine is a 1986 Yanmar 4JH HTE turbo. I am planning to do cruising/diving in Indonesia and South Pacific starting Oct 2013. After that, will decide if I have the guts to head up to Alaska/PNW or stay put around Australia/NZ.

After reading Yanmar Problems on noelex 77 reply on the removal of turbo, I like to have a straight pipe as spare should the turbo acts up in future.

I can see a naturally aspirated engine has many advantages + some loss of power.

My question is besides the straight pipe to replace the turbo unit, do I have to replace the injectors, recalibrate injector pump and reprop?

I am not an expert in engine and my 2 cents guess is there is no need.

There is no problem with the engine now.

What are your thoughts and experience?

All ideas and suggestions are most appreciated.

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Eric
Port Klang, Malaysia
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Old 24-03-2013, 19:22   #2
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Re: Yanmar 4JH HTE - Remove Turbo

Eric:

I don't specifically know that engine, but most turbocharged engines have a lower compression ratio (which is made up for in boost) than their NA brothers. This will mean lower efficiency and maybe poor combustion at higher rpms without the turbo.

But why not just pull the throttle back and not use the turbo? Turbos themselves when not impacted by water in the exhaust, etc. are very low maintenance items and should last many thousands of hours.

David
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Old 27-03-2013, 11:21   #3
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Re: Yanmar 4JH HTE - Remove Turbo

Hi David,

Thank you for the reply. I will leave the engine alone for now and enjoy
cruising in Phuket first.

Eric
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Old 27-03-2013, 21:41   #4
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Re: Yanmar 4JH HTE - Remove Turbo

As noted, the turbo versions are not just the non-turbo versions, with the added turbo.

1) Your engine will work at lower RPMs, without the turbo. But, not well, and you will not be doing long-term good to your engine.

2) Keeping the turbo clean and operational is a matter of maintenance. I know, because I suck at this! Run the heck out of your turbo, on a regular basis. Yanmar recommends using their Turbo Wash to keep it clean. Their recommendation? "once a week". Seriously.

3) Removing the turbo is a 1/2 day job, as is putting it back on. I've done this twice. The turbo can be cleaned when you take it out. Do NOT pry on the vanes. The turbo spins at 70,000 to 80,000 rpms!

4) You can buy a rebuild kit for about $150. ANY turbo shop in the world can rebuild it - these IHI turbos are common on cars all over the world. YOURS has been modified to the Yanmar engine, but it is essentially the same as all of the others. Not interchangeable, but similar.

Repeat #2 as often as you can remember.
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Old 27-03-2013, 21:50   #5
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Re: Yanmar 4JH HTE - Remove Turbo

Doesn't the HTE also have a heat exchanger (inter cooler) after the turbo to cool the air after it is compressed? I don't know how that would work without the turbo.
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Old 30-03-2013, 09:19   #6
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Re: Yanmar 4JH HTE - Remove Turbo

Bill: Yes I see your point here. Have to learn to do the regular maintenance. Thanks.

DeepFrz: That would be tough to remove. Will take a look at the engine when get to the boat next visit. Thanks.
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