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| How to tell the difference between Vo... |
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kevman1421
New member
Username: kevman1421
Post Number: 3
Registered: 05-2011
| | Posted on Thursday, May 19, 2011 - 01:56 pm: | 
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Thought this might help someone trying to figure it out..
I was told by a person who traded me for my volvo, that his ACE/GURU mechanic "who had rebuilt 100's of VOLVOs" said my engine was not a MD2B and several other false things.
Someone wasn't telling the truth either intentionally or accidently and this led to a bad feelings on both sides.
Since I'm not an Volvo ACE/GURU myself, I had to do some digging to find this out what was going on.
Visually the engines look almost identical from the outside but there is an EASY WAY to Identify these two engines.
On the MD2B look @ the intake side ,(portside)of the engine @ the valve/rocker cover.
There will be two (2) bolt heads @ the corner of the head, just OUTSIDE of the valve cover.
These are # 5 & #6 head bolts.
The MD2 DOES NOT have these 2 "extra" head bolts.
There are only 4 head bolts on the MD2.
These extra 2 Head bolts END in THE CYLINDER.
They are much shorter than the other 4 (which are actually Studs) that run thru the cylinder & into the block.
They are also smaller in diameter and their torque is less. (33 ft.lb vs 80 ft.lb) for the 4 larger ones.
Two of the 4 larger headbolts/studs are under the valve/rocker cover and 2 are on the outside of the cover on the right/starboard side.
These 4 larger ones are common to both types.
See the pictures below.
Many of the pictures in the MD2B manual are actually stock photos of MD2 engines and labeled as MD2B engines.
Either Volvo didn't know or didnt care to change them in the manual so it is a little confusing.
However,.... MOST but NOT ALL of the pictures showing head work or cylinder work ARE of the MD2B engine,...... some are not.
Also many engines shown on the internet and youtube and such are listed as one or the other when they are not.
Even a museum engine has the wrong info printed under it. So this is confusing @ best.
Most parts are not interchangable however
I will have to look some more and see if the actual BLOCK is different.
If they are the same then this may be one of the reasons that many engines are listed as MD2 and not MD2B because the data plates or serial #s may indicate the older MD2 and possibly the upper end has been replaced w/ MD2B parts.
THIS IS not a fact , just a possibility IF they share the same block.
I have NOT looked into this yet.
Maybe someone else with intimate knowledge
(a real Volvo GURU) of these engines can chime in and clarify this.
Cheers,...Kev
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Dave Wheatley
Visitor
| | Posted on Thursday, May 26, 2011 - 05:42 am: |
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Thanks for that Kev. While we are on subject of engine differences, do you you know the important differences between MD2B and MD11C? I know that the md11c has cylinder liners whereas the MD2B has 'solid' blocks. I have a MD2B in the boat and a spare MD11C.
Dave |
matt_morehouse
Senior Member
Username: matt_morehouse
Post Number: 91
Registered: 12-2009
| | Posted on Thursday, May 26, 2011 - 09:41 am: |
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Another dead sure way to tell the MD2 from the MD2B is by bore: the MD2 is 79.37mm, the MD 2B is 88.9mm. The stroke is 90mm in both, so maybe the lower end is the same, I can't remember.
The MD2 makes 15.5hp@2300rpm, the MD2B makes 25hp@2500rpm. |
adsum
Member
Username: adsum
Post Number: 29
Registered: 01-2008
| | Posted on Thursday, June 02, 2011 - 04:12 pm: |
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When I overhauled the lubrication oil pump of my MD2B it didn't look like the picture in the manual. I guess the picture is the old MD2 pump. That confirms Kev's remark about the old MD2 stock photos in the MD2B manual. The improved lubrication oil pump might be another difference between MD2 and MD2B |
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