Volvo Penta D2-55 Pistons the wrong way around

[jimbunyard]

Originally Posted by AROsailing

Thanks for all the input Guys.. it’s much appreciated.. Is the general opinion that this engine could have run in charter for 8 years like this without damage?

Yes, but not without wear, which is why subsequent posts have raised pertinent questions.

With 6000+ hours, replacing rings, rod bearings, main brgs, a valve job and maybe a new oil pump or oil pump gears should be taken as a given; to have the engine apart with that many hours and not to replace them is a-economical.

If you had good oil pressure and the engine ran well previously, there's no reason not to expect another 6000 hrs with just such a bare bones 'rebuild'.

But---careful consideration should be given to measurement of the pistons and bores; if it were me and I could afford it I'd likely replace them regardless of whatever measurements I came up with, along with a good cylinder honing.

The reasoning? When a cylinder fires, the forces are not directed evenly across the top of the piston; therefore the cylinder and bore wear differently on opposite sides. Swap them 180 and the differences in wear may or may not allow the rings to seat efficiently.

As a rough example, about 10 or 12 years ago I rebuilt a ski/fishing boat for a friend on a budget, and included was rebuilding a 350 Chevy that was locked solid, meaning a new block. So I bought a used truck short block for 100.00, and combined the two engines into one. Since we were on a budget, turns out that I had to use one piston assembly from the right bank on the left, and since I couldn't disassemble it, I put it in upside down so the valve recesses were correctly aligned.

Well the engine ran fine, full power, for around six years, but it burned oil like a two stroke. I mean about a quart every 50 miles. Compression was within 20 lbs on all cylinders, I even removed the intake to make sure there wasn't a problem there. So he just ran it like that for 6-7 years.

Kind of irritated me and I was curious so, I told him I'd rebuild it properly for the cost of the parts and 100.00. I was curious what I'd find, and suspected a collapsed or broken oil ring on the inverted cylinder.

I was surprised to find that all the rings were good, and besides the inverted piston, everything looked good. So I had the block bored and honed, put new oversize pistons in it, and put it back together, and it runs very well indeed with no oil burning at all.


To answer your question about the Perkins/Volvo cross, as far as I can determine that is accurate; the specs across the respective sales literature are identical. To make sure before ordering parts a call to the supplier is in order.

As an example, here is a kit with all the relevant parts for 675.00.



https://www.tractorpartsdirect.com/P...Overhaul-Major

[DougR]

The reason the valves didn't hit the piston is that the recess which you see on the piston top is not for valve clearance at all, and the valves are not aligned over the recess whether the piston is reversed or not.

The D2-55 engine ( Perkins 404C & 404D for later models) is an IDI engine, indirect injection, and the injectors inject fuel into a pre combustion chamber located in the cylinder head which is connected to the main cylinder volumn via a small diameter tangentially positioned passage. The purpose of the figure 8 shaped recess on the piston top is to direct air into the pre chamber as the piston rises and then receive the high pressure flow back out of the pre chamber after injection. The small "notch" at the side of the figure 8 aligns with the passage into the pre chamber. Nothing to do with valve clearance...

If the pistons were in fact installed turned 180, the combustion efficiency would have suffered from poor gas flow and flame propegation across the piston top, and could have helped with the plugged exhaust elbow.

When the D2-55 engine was introduced the first versions (A & B) were fitted with 60 amp alternators and the alternator was driven by a single V belt. Somewhere around 2004 or 2005 they made some changes to the heat exchanger design and changed the nomenclature to the D2-55C. Also at that time they upgraded to a 115 amp alternator and drove that alternator with a serpentine belt system. The serpentine belt pulleys have been available ever since.

DougR

[Compass790]

Originally Posted by DougR

The reason the valves didn't hit the piston is that the recess which you see on the piston top is not for valve clearance at all, and the valves are not aligned over the recess whether the piston is reversed or not.

The D2-55 engine ( Perkins 404C & 404D for later models) is an IDI engine, indirect injection, and the injectors inject fuel into a pre combustion chamber located in the cylinder head which is connected to the main cylinder volumn via a small diameter tangentially positioned passage. The purpose of the figure 8 shaped recess on the piston top is to direct air into the pre chamber as the piston rises and then receive the high pressure flow back out of the pre chamber after injection. The small "notch" at the side of the figure 8 aligns with the passage into the pre chamber. Nothing to do with valve clearance...

If the pistons were in fact installed turned 180, the combustion efficiency would have suffered from poor gas flow and flame propegation across the piston top, and could have helped with the plugged exhaust elbow.

When the D2-55 engine was introduced the first versions (A & B) were fitted with 60 amp alternators and the alternator was driven by a single V belt. Somewhere around 2004 or 2005 they made some changes to the heat exchanger design and changed the nomenclature to the D2-55C. Also at that time they upgraded to a 115 amp alternator and drove that alternator with a serpentine belt system. The serpentine belt pulleys have been available ever since.

DougR

Thanks for educating us. Assumed it was direct injection as thought indirect injection engines use flat top pistons (Never assume!) Be interesting to know if they are lined up with the pre-combustion chamber. Funny thing is wondered why flame marks didn't seem 180o out.
Apology to O.P. from me for wrong diagnosis. Hope he posts again to say wether they line up with pre combustion chamber as is if he hasn't removed already

[AROsailing]

Originally Posted by DougR

The reason the valves didn't hit the piston is that the recess which you see on the piston top is not for valve clearance at all, and the valves are not aligned over the recess whether the piston is reversed or not.

The D2-55 engine ( Perkins 404C & 404D for later models) is an IDI engine, indirect injection, and the injectors inject fuel into a pre combustion chamber located in the cylinder head which is connected to the main cylinder volumn via a small diameter tangentially positioned passage. The purpose of the figure 8 shaped recess on the piston top is to direct air into the pre chamber as the piston rises and then receive the high pressure flow back out of the pre chamber after injection. The small "notch" at the side of the figure 8 aligns with the passage into the pre chamber. Nothing to do with valve clearance...

If the pistons were in fact installed turned 180, the combustion efficiency would have suffered from poor gas flow and flame propegation across the piston top, and could have helped with the plugged exhaust elbow.

When the D2-55 engine was introduced the first versions (A & B) were fitted with 60 amp alternators and the alternator was driven by a single V belt. Somewhere around 2004 or 2005 they made some changes to the heat exchanger design and changed the nomenclature to the D2-55C. Also at that time they upgraded to a 115 amp alternator and drove that alternator with a serpentine belt system. The serpentine belt pulleys have been available ever since.

DougR

Hi DougR, and thanks for your input it is much appreciated.
I have left the motor in the hands of a marine engineer as the boat is now in Greece and I'm without the available tools or facilities.
The pistons have indeed been removed from the block.
From what I understand from your post above, it is possible that the pistons weren't installed the wrong way around and the notch on the side of the figure eight is the critical alignment factor. Am I understanding your post correctly.
As I'm no longer in direct contact with the motor, the last thing I want is for the rebuild to result in the placing of the pistons incorrectly. As the general assumption was that That the piston recesses were to align with valves.

[jimbunyard]

Just for grins, since I don't understand the use of the word tangentially here, does the 'notch' go directly under the injector 'port', of does it go across from it, on the other side of the cylinder, as it were, and the injector 'shoots' across the top of the piston?

As seen in the last picture, the injectors are at a pretty steep angle...

[Milko Berben]

I go with Kryg at app. 6000 hours you are about half way the lifespan of this engine
my generator has about 13,000 hours on it and runs still beautifully they are super engines but when you run them make sure you load it properly so that you don't get a build of coke because of low temp good luck with your reassemble. Maybe just change the conrod big end bearings it is easy and you will have a good oil pressure.

[DougR]

The installation of the pistons is described in the service manual, so if the shop doing the installation follows the manual they should get it correct. Specifically the instructions call for the cast in markings on the underside of the piston to be aligned with the markings on the connecting rod, and then the conrod installed with the markings toward the camshaft side of the engine.

When I used the word tangentially, I was describing the physical relationship between the passage into the pre chamber and the body of the pre chamber. Inotherwords, the passage enters the circular void of the pre chamber along its edge. This imparts an intense "swirl" to the air within the pre chamber and this swirl serves to breakup and quickly vaporize the fuel as it is being injected.

DougR

[Compass790]

I too am curious & have the same question as jimbunyard about the notch. Since you know this engine, when the piston is installed [B]according to the workshop manual instructions, does the notch line up with the precombustion chamber outlet?

[Compass790]

Originally Posted by DougR

The installation of the pistons is described in the service manual, so if the shop doing the installation follows the manual they should get it correct. Specifically the instructions call for the cast in markings on the underside of the piston to be aligned with the markings on the connecting rod, and then the conrod installed with the markings toward the camshaft side of the engine.

When I used the word tangentially, I was describing the physical relationship between the passage into the pre chamber and the body of the pre chamber. Inotherwords, the passage enters the circular void of the pre chamber along its edge. This imparts an intense "swirl" to the air within the pre chamber and this swirl serves to breakup and quickly vaporize the fuel as it is being injected.

DougR

Actually after looking at head it appears that the only reason for the notch would be to line up with injection port AFAI can see so I'm picking whatever the w/shop manual says how to line it up that's how its going to end up
I can see your point DougR