Maintenance - Trouble reviving engine

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Trouble reviving engine

Printed From: Laser 28 International Class Association
Category: Laser 28 General
Forum Name: Maintenance
Forum Description: All the things to care for your boat
URL: http://www.laser28.org/forum/forum_posts.asp?TID=891
Printed Date: 22 November 2024 at 9:39pm
Software Version: Web Wiz Forums 11.03 - http://www.webwizforums.com

Topic: Trouble reviving engine

Posted By: fatjohnz
Subject: Trouble reviving engine
Date Posted: 23 January 2023 at 10:16pm

It's a long story.
My original engine failed with a puff of white smoke from the transom and water in the oil. I took the head to my local machine shop. After cleaning and inspection, he showed me that the water jackets were corroded, and the head was compromised.
Keith from Crinmar suggested I send the head to Canada where a local shop had 50/50 success trying to recover these heads. I sent the head away and repowered my boat with a salvage engine.
Months and months later, a box arrived. A head of better condition was in the box. I'm not sure if it was the same as I sent but it was in better shape.
I cleaned the water jackets of the cylinder; they were clogged with metal flakes. I mention that because I'm not sure where the engine failed in the first place. I pulled the head as the first usual suspect. I put the head back on the cylinder and tried to fire it up.
I have not been able to get a 'pop' out of the engine even with starter fluid sprayed straight into the intake. I had already set the valve lash to loose and the valves are closing. When I remove the injector and cycle the engine, I can feel quite a bit of compression.
I'm recalling now that I never confirmed the deck of the cylinder or the deck of the head for that matter. I guess I've assumed the deck of the head was checked while it was in Canada.
I asked my local machine shop what to check for. They said I could check the valve security by putting some liquid around the valve seats to see if they leak. The shop does not have a compression tester for diesel. I'm thinking I would check compression on my own before pulling the head again.
I see I can get a 300 psi compression tester with rubberized tip that should work with the Bukh. Do you know what the compression should read?
I need some guidance on how to bring this engine back to life.... thanks, John

Replies:

Posted By: Foghorn
Date Posted: 14 February 2023 at 12:11pm

The actual compression on the Bukh is not high for a diesel, from memory about 16:1. I've seen them run with pretty low compression.

I'm wondering if perhaps you might have the pushrods actuating the wrong rocker. Might be worth establishing TDC and rotating the motor through 2 revolutions to ensure all is well.

-------------
Paul White
Decompression
CAN 214

Posted By: fatjohnz
Date Posted: 18 February 2023 at 9:07am

Thanks Paul,
I'll keep y'all posted. I did check the valves were opening and closing and checked the lash. It's possible the rods are in the wrong seats but I did my best to follow the instructions. I would think that even if they were out of sequence, the engine would pop. When I have the injector out, I'll find TDC and report the valve opening sequence.
Other recommendations I've been given are to confirm the injector is pushing fuel. Also to remove the head and float some fuel around the valve seats to make sure they are sealing. Once I have the head off, I'm hoping that a local machine shop could check the head deck and the cylinder deck. I assume the head was checked when it was reconditioned but I did not have the cylinder checked. The cylinder had a lot of debris in the water jackets so I'm wondering if it contributed to the original head gasket failure. I suppose once I get this far, I should consider new rings.
Any other suggestions are welcome.
Thanks, John

Posted By: fatjohnz
Date Posted: 05 April 2023 at 10:58am

I was thinking; I wish I knew the name of the Canadian machine shop that Keith from Crinmar sent my engine's head for reconditioning. I thought @frfletch mentioned them but did not say their name/location. I would like to contact them about checking out the rest of the cylinder.
Does anyone know?

Posted By: Foghorn
Date Posted: 20 April 2023 at 6:39pm

United Welding Processes (UWP)

uwp.ca

-------------
Paul White
Decompression
CAN 214

Posted By: fatjohnz
Date Posted: 15 June 2023 at 9:29am

@Foghorn, I didn't find an absolute compression number in the forum but if I converted your 16:1 compression ratio correctly I get 235 psi. I could check this with a cheap auto tester. Do you have a feel for what psi reading I would see when cranking on the starter?

Posted By: Foghorn
Date Posted: 16 June 2023 at 4:46pm

The actual compression ratio is 18.4:1

On that basis, at sea level the PSI should be around 270 PSI.

Cheers

-------------
Paul White
Decompression
CAN 214

Posted By: fatjohnz
Date Posted: 25 July 2023 at 9:32am

A compression check yielded 150psi :-(
I pulled the cylinder yesterday, which was no easy trick.
My tentative plan is to
- check the valve seals w/ some liquid while the head is inverted
- have a machine shop check the mating surfaces on the head and cylinder decks?
- get some rings and a block gasket on order (I already have head gaskets)
I'm deeper into this than I thought I'd get. What else should I do now... attempt to change the piston bearings?
Thanks for any advice, john