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Volvo Penta AQ171C - large crack

DT2748

New member
Recently purchased a boat that had not been used for 10+ years. It has the AQ171C engine in it. I bought the boat with some friends - basically it was only a few dollars (literally). It is a restore project - so if we think it is north worth tryng to repair, we will get rid.

It had collected a lot if rain water however after much pumping of water from it, we got a view of the engine. We noticed the large crack - see pics.

Question is, is it even worth repairing?

I am a complete boat novice. Any info would be much appreciated.

Thanks
DT
 
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Can't see any pictures, but if the crack is in the block then a simple block swap would be easy to do. You can use any B230 block. The extra capacity of the 171 comes from the stroke, not the bore, so as long as you swap all the 171 bits onto the new block you will still have a 2.5litre 167hp engine.
 
Crack as shown is in the exhaust manifold/elbow casting which is a "bolt on" part. You would need to do a compression check next to get an idea of the health of the block itself..

It appears, based on your narrative and the pix that the rust shows the high water mark. FIRST thing I'd check is if the top of the dip stick is well above this high water mark. IFSO, there is some hope. Next drain the oil ( preferably via the oil pan drain) and inspect for water in the oil.
 
As mentioned, exhaust manifold is a bolt-on part. Not cheap, but less and easier than an engine rebuild. Does engine turn over ok? If so do a compression test and if ok, probably worth spending money on getting it going. These Sealine 195s are nice little boats. Whatever you do, if going ahead with the project, get the cam belt changed before running it. If the boat has been sat for years, it will be ready to snap and will trash the engine. In fact maybe even get it changed before compression test, unless you feel lucky.
 
re: "In fact maybe even get it changed before compression test, unless you feel lucky. " DITTO!!!!... or even cranking it more than to check that its not frozen. Before you do this first remove the spark plugs and squirt a very small small amount of transmission fluid into each cylinder and try to "bump" it with the starter with the plugs out. If you have access to a bore scope, visually inspect the cylinder bores for rust immediately after you remove the plugs and before you squirt anything in. A very light dusting of rust may be survivable... "serious rust" not. Ten years is.... forever...
 
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As mentioned, exhaust manifold is a bolt-on part. Not cheap, but less and easier than an engine rebuild. Does engine turn over ok? If so do a compression test and if ok, probably worth spending money on getting it going. These Sealine 195s are nice little boats. Whatever you do, if going ahead with the project, get the cam belt changed before running it. If the boat has been sat for years, it will be ready to snap and will trash the engine. In fact maybe even get it changed before compression test, unless you feel lucky.

Many thanks for the advice - much appreciated!
 
From what I see with a water line that high ,it`s junk. water most likely entered the rear housing and drive and engine. If the manifold cracked, the block is most likely cracked also
 
From what I see with a water line that high ,it`s junk. water most likely entered the rear housing and drive and engine. If the manifold cracked, the block is most likely cracked also

Many thanks for your post. If it turns out you are right, is it best to get rid of boat + dud engine inc trailer or...

Seek a replacement engine?
Does replacement engine need to be the same - or can it be a different manufacturer?
Convert to outboard?

Best Regards
 
Many thanks for your post. If it turns out you are right, is it best to get rid of boat + dud engine inc trailer or...

Seek a replacement engine?
Does replacement engine need to be the same - or can it be a different manufacturer?
Convert to outboard?

Best Regards

easiest replacement is like-for-like. You can use a standard B230 Volvo block as found in many 80s 90s Volvo cars as long as you use ALL the other bits of your engine, including crank, pistons, head etc etc.

personally I don't think the rust is a tide line. I think it's just water that has leaked out of the exhaust. Don't write it off just yet. Do you have a photo of the other side of the engine? That might help clear it up.
 
easiest replacement is like-for-like. You can use a standard B230 Volvo block as found in many 80s 90s Volvo cars as long as you use ALL the other bits of your engine, including crank, pistons, head etc etc.

personally I don't think the rust is a tide line. I think it's just water that has leaked out of the exhaust. Don't write it off just yet. Do you have a photo of the other side of the engine? That might help clear it up.


Hi..Many thanks for the reply - see attached.

Will try and get some better pics tomorrow.

engine - other.jpg
 
A couple of questions if I may...
I run a pair of AQ171’s so know them fairly well.
They need a lot of looking after and you need to be at least keen “mechanic” as they tend to be fragile after 30+ years.
I would heed the advice of others regarding checking oil levels, compression, timing belt etc
Is the rust shown in your last photo a result of the rain water before pumping out?
The first thing I would do is to remove the exhaust manifold to check the condition of the cylinder head. This is heavy by the way.
Any luck and the exhaust manifold is just cracked on one side.
Replacement exhaust manifolds are very rare, expensive and only occasionally turn up on your favourite auction site. I replaced mine with new stainless steel exhaust manifolds, but you need to know everything else looks o/k before open wallet surgery!
Remove spark plugs and see if the engine turns over by hand. Check if any water comes out of the cylinder head or spark plug holes.
You may find that the pistons are seized due to water / condensation ... you could try pouring diesel into the spark plug holes and leaving for a few days.
You really need a workshop manual to guide you through.
For inspiration there are a couple of web videos of someone who completely overhauled an AQ171c on a Fjord Dolphin... worth checking out.
When working they are great engines, fairly economical as gasoline engines go.. If all else fails the High Performance Volvo Club website will jump at getting their hands on an AQ171c.
Good luck.
 
If we are to assume the yellow line represents the water level judging from the rust line and would match the rust stain and crack on the opposite side of the motor everything that was underwater will need replacing.
click to enlarge
 
If we are to assume the yellow line represents the water level judging from the rust line and would match the rust stain and crack on the opposite side of the motor everything that was underwater will need replacing.
click to enlarge

you would expect to see a corresponding 'tide' line all around the engine bay if water had been that high, so the question to the original poster. Is there a tide line in the engine bay?
 
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