Performing compression test on Penta - SailNet Community
 2Likes
Reply
 
LinkBack Thread Tools
post #1 of 18 Old 11-23-2012 Thread Starter
baDumbumbum
 
bobmcgov's Avatar
 
Join Date: Jul 2007
Location: Windy Wyoming
Posts: 1,121
Thanks: 0
Thanked 36 Times in 35 Posts
Rep Power: 8
 
Performing compression test on Penta

We have the original MD6A Volvo Penta on our new-to-us boat. Whether we keep it and go to the trouble of converting the cooling and exhaust systems has a lot to do with the condition of the pistons and valves. It has the Bosch injectors (held in by yoke washers) and no glow plugs; what adapters do we need to perform a simple compression test? The engine is already winterized, so we'd like to do the test cold. The specs in the owner's manual are 285-340 psi at starter/generator RPM.

Buccaneer18, Grainnia
SJ21, Diarmuid
Albin Ballad 30, Fionn
bobmcgov is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 18 Old 11-23-2012
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 16,382
Thanks: 101
Thanked 304 Times in 294 Posts
Rep Power: 10
     
Re: Performing compression test on Penta

The volvo part number appears to be 9988539-4 compression gauge..probably not cheap... and maybe even not a match for your model...

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Faster is online now  
Quote Quick Reply Share with Facebook
post #3 of 18 Old 11-23-2012
Banned
 
Join Date: Jul 2007
Location: Truckee, CA
Posts: 8,591
Thanks: 2
Thanked 116 Times in 114 Posts
Rep Power: 0
 
Re: Performing compression test on Penta

Have done lots of comperssion tests on gas engines, but none on diesels. If it starts without excessive cranking or ether and runs well without smoking the compression may be within specs. I read where someone added a little oil, as can be done with gas engines when worn rings are suspect, and it made the diesel fire. Seems like a bit of a stretch but diesels do run on thin oil?

Paul T
dabnis is offline  
Quote Quick Reply Share with Facebook
post #4 of 18 Old 11-23-2012 Thread Starter
baDumbumbum
 
bobmcgov's Avatar
 
Join Date: Jul 2007
Location: Windy Wyoming
Posts: 1,121
Thanks: 0
Thanked 36 Times in 35 Posts
Rep Power: 8
 
Re: Performing compression test on Penta

Yeah, we're trying hard to avoid anything with the name 'Volvo' attached to it. These are pretty standard Bosch injectors, tho I can't measure the length or aperture until they are pulled. Probably 24mm. I just need the right adapter so any garden-variety diesel compression gauge can read it.

When we change over from raw to fresh water cooling and wet exhaust, we'll be fabricating our own mixing elbow, too. If you can even find a Volvo elbow, they cost ~$500.

Doesn't take too many OEM Volvo parts to make a total re-power the preferred option. We want 4 seasons or so out of this engine before we swap out. If the internals are solid. No hour meter, sadly.

Buccaneer18, Grainnia
SJ21, Diarmuid
Albin Ballad 30, Fionn
bobmcgov is offline  
Quote Quick Reply Share with Facebook
post #5 of 18 Old 11-23-2012
Senior Member
 
Join Date: Oct 2011
Location: Nanaimo B.C.
Posts: 2,351
Thanks: 3
Thanked 47 Times in 47 Posts
Rep Power: 4
 
Re: Performing compression test on Penta

Real carefull there, Not much room for oil at TDC.
Capt Len is offline  
Quote Quick Reply Share with Facebook
post #6 of 18 Old 11-23-2012
Senior Member
 
Join Date: Oct 2011
Location: Nanaimo B.C.
Posts: 2,351
Thanks: 3
Thanked 47 Times in 47 Posts
Rep Power: 4
 
Re: Performing compression test on Penta

Better to start and run. watch for smoke and oil pressure from cold to hot. (shows condition of bearings) Mixer easy to make with adapter plates and NPT pipe fittings. Make a second at same time to make sure you're good for the 4 years. Weld the nipple at a good angle well below the hot part.
Capt Len is offline  
Quote Quick Reply Share with Facebook
post #7 of 18 Old 11-23-2012
Tartan 27' owner
 
CalebD's Avatar
 
Join Date: Jan 2008
Location: NYC
Posts: 4,721
Thanks: 4
Thanked 106 Times in 98 Posts
Rep Power: 8
 
Re: Performing compression test on Penta

So Bob, where will you be sailing your new-ish Albin 30'?

You are right about the Volvo OEM parts. Enough of those and you could buy a Beta marine brand new diesel (~ $6K). Kubota tractor dealers carry most of the replacement parts at a major discount.

"The cure for anything is salt water~ sweat, tears, or the sea." ~Isak Denesen

Everybody has one:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CalebD is offline  
Quote Quick Reply Share with Facebook
post #8 of 18 Old 11-24-2012
Seor Member
 
PorFin's Avatar
 
Join Date: Sep 2007
Posts: 1,444
Thanks: 8
Thanked 18 Times in 18 Posts
Rep Power: 8
 
Re: Performing compression test on Penta

Bob,

Not sure if it will help, but I faced a similar challenge on our Perkins 4.108 which also uses yoke style injector hold-downs.

I picked up a cheapo diesel compression tester at Harbor Freight. It has a quick disconnect (QD) fitting, but no adapters that were usable on the 4.108.

What I wound up doing was to disassemble an old injector to remove the guts. I swapped out the fuel inlet fitting with the QD fitting. I reassembled the injector body leaving out the needle & springs. I also blocked off the fuel return/overflow path.

It took a couple of test runs to make sure it was holding, but ultimately it worked fine.
Faster and bljones like this.
PorFin is offline  
Quote Quick Reply Share with Facebook
post #9 of 18 Old 11-24-2012
Banned
 
Join Date: Jul 2007
Location: Truckee, CA
Posts: 8,591
Thanks: 2
Thanked 116 Times in 114 Posts
Rep Power: 0
 
Re: Performing compression test on Penta

Before going to all that work, you might consider an oil analysis, supposedly it will show worn bearings and/or rings in addition to unburnt fuel contamination.

Paul T
dabnis is offline  
Quote Quick Reply Share with Facebook
post #10 of 18 Old 11-24-2012 Thread Starter
baDumbumbum
 
bobmcgov's Avatar
 
Join Date: Jul 2007
Location: Windy Wyoming
Posts: 1,121
Thanks: 0
Thanked 36 Times in 35 Posts
Rep Power: 8
 
Re: Performing compression test on Penta

Quote:
Originally Posted by CalebD View Post
So Bob, where will you be sailing your new-ish Albin 30'?

You are right about the Volvo OEM parts. Enough of those and you could buy a Beta marine brand new diesel (~ $6K). Kubota tractor dealers carry most of the replacement parts at a major discount.
Three or four years to refit completely, then down to the Pacific. Probably keep the boat in San Carlos, MX. Would like to hit Vanuatu, Tonga, someday. That's a ways off. Need to replace those sketchy thru-hulls first. Adore the Beta engines. Outside our refit budget, tho.

PorFin: Thanks! I might try that approach. We also have a huge number of eager, impoverished young diesel mechanic trainees in town (big technical college). I might find a couple of them to run the diagnostics, maybe overhaul the injectors, maybe even the whole engine. Tho again, we don't want to pour too much into an engine that has a) been fresh-water cooled its whole life, albeit in the Great Lakes; and b) will be an ongoing source of trouble/expense. I'd like a solid notion of what hours it has left before we commit to major repairs or modifications.

Suppose "ongoing source of trouble/expense" pretty much describes marine engines in general....

Buccaneer18, Grainnia
SJ21, Diarmuid
Albin Ballad 30, Fionn
bobmcgov is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Test running an old Volvo Penta while in storage? chefuno General Discussion (sailing related) 8 10-15-2012 11:08 AM
Compression test brokesailor Pacific Seacraft 14 02-09-2011 08:48 AM
MD6A compression test adaptor.. groundhog Gear & Maintenance 2 06-14-2007 01:50 PM
Compression test w/o turning off water thru-hull rbtmoon Atomic 4 1 06-12-2006 06:16 PM
Compression test w/o closing thru-hull water rbtmoon Atomic 4 0 06-12-2006 11:30 AM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome