Reply
 
Thread Tools Search this Thread
 
Old 29 June 2019, 07:52   #1
Member
 
Country: UK - Scotland
Town: Largs
Boat name: Tunnag
Make: Redbay 8.4
Length: 8m +
Engine: Diesel inboard. Yam
Join Date: Jun 2019
Posts: 7
Yamaha 421 boost issues?

Hi guys.

So my turbo failed (lost a exhaust blade due to carbon build up). I have had it reconditioned from universal turbos, but now I have significant turbo howl and a lot less power.

With a full load the boat has to be WOT throttle for a good 15 seconds before the turbo kicks in and she is gets up on the plane.

I get the same revs and speed at WOT. Just seems to be lack of power to get out the hole.

Turbo was sent back and itís confirmed all is correct now.

The noise from turbo is so much louder than before

Next thing I will look at intercooler.

Anyone have any advice or similar issues?

Boat is Redbay 8.4.

Cheers.
__________________

__________________
RBJT is offline   Reply With Quote
Old 29 June 2019, 08:11   #2
Member
 
RAS666's Avatar
 
Country: UK - England
Town: Ormskirk
Boat name: Viktor
Make: Avon Sr4
Length: 3m +
Engine: Mercury 50 / 2hp ele
Join Date: Sep 2018
Posts: 17
Did you recover the missing blade from the rest of the exhaust system?
__________________

__________________
RAS666 is offline   Reply With Quote
Old 29 June 2019, 10:17   #3
Member
 
Country: UK - Scotland
Town: Largs
Boat name: Tunnag
Make: Redbay 8.4
Length: 8m +
Engine: Diesel inboard. Yam
Join Date: Jun 2019
Posts: 7
Quote:
Originally Posted by RAS666 View Post
Did you recover the missing blade from the rest of the exhaust system?


No. Surely it will be out the exhaust and in the Clyde now?
__________________
RBJT is offline   Reply With Quote
Old 29 June 2019, 11:28   #4
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 2,165
Is it the engine with the pressure operated boost control on the back of the intercooler or the straight through one? If it has the control then it may not be operating stifling the boost. The other thing to check is fit a pressure guage into the inlet manifold to measure the boost
__________________
beamishken is offline   Reply With Quote
Old 03 July 2019, 08:27   #5
Member
 
Country: UK - Scotland
Town: Largs
Boat name: Tunnag
Make: Redbay 8.4
Length: 8m +
Engine: Diesel inboard. Yam
Join Date: Jun 2019
Posts: 7
Quote:
Originally Posted by beamishken View Post
Is it the engine with the pressure operated boost control on the back of the intercooler or the straight through one? If it has the control then it may not be operating stifling the boost. The other thing to check is fit a pressure guage into the inlet manifold to measure the boost


Hi ken.

I think itís the later model with the straight through set up.

Will start stripping the intercooler tonight to see how that looks.
__________________
RBJT is offline   Reply With Quote
Old 03 July 2019, 10:16   #6
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 2,165
Theres likely a boost pressure compensator pipe goes to the pump on that one, be worth checking the pipe is clear if it has it cant remember where it is but with no boost pressure regulator or waste gate there must be something tells the pump to fuel up when the boost comes in
__________________
beamishken is offline   Reply With Quote
Old 05 July 2019, 15:31   #7
Member
 
Country: UK - Scotland
Town: Largs
Boat name: Tunnag
Make: Redbay 8.4
Length: 8m +
Engine: Diesel inboard. Yam
Join Date: Jun 2019
Posts: 7
Quote:
Originally Posted by beamishken View Post
Theres likely a boost pressure compensator pipe goes to the pump on that one, be worth checking the pipe is clear if it has it cant remember where it is but with no boost pressure regulator or waste gate there must be something tells the pump to fuel up when the boost comes in


Hi mate.
IC all clear, but cleaned anyway.
The pipe your talking about is it a wee rubber one that goes from the top of pump to the manifold? If so all clear and in tact.

I am lost.

Now going to borrow a turbo from a mate and try that to see if the new (remanufactured) turbo is not correct.

Any other ideas much appreciated.
__________________
RBJT is offline   Reply With Quote
Old 06 July 2019, 06:05   #8
Member
 
Country: UK - England
Town: Southern Uk
Length: 8m +
Join Date: Jul 2019
Posts: 7
Have you tried fitting a boost pressure gauge to the inlet manifold? And checking you boost pressure..

Maybe you have a boost pressure leak.. Have you checked all the boost hoses?
__________________

__________________
Gareth231 is offline   Reply With Quote
Reply

Tags
yamaha

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 19:30.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.