CDK
08-31-2007, 06:16 AM
The background for this topic is "from sterndrives to jets to surface drives" on the surface drive forum: http://forums.boatdesign.net/showthread.php?t=18742.
I am presently converting two small VW engines (1.9TD) for their marine future and come across various issues.
Every article I read about converting car engines points out that you should make sure the engine is in good condition, like no oil leaks, not much smoke, abnormal noises etc. But if you buy an engine from a recycling company, like I did, the part has been removed from the wrackage with crude tools like a flex and a bolt cutter. All wiring, bowden cables and hoses have been cut off, the oil has been drained and the exterior pressure cleaned. Just to start up the engine to check if it runs at all, requires the purchase of various items left in the car, like a glow plug relay, starter switch and basic wiring. Also a complete cooling system has to be built: with the 6 cut off hoses the engine was deliverd with, even a short test run might prove fatal.
For this specific engine, a further problem is, that in the VW Transporter the engine is attached to a combined bell housing/gear box that also holds the starter motor. That part is sold separately for approx. $400 but is unsuitable for a marine engine because a marine gearbox should be attached.
So I work on the assumption that the supplier is a decent guy until proven otherwise....
From 1/4" mild steel plate and some 1/2" pipe I have constructed a bell housing with a large hole that fits the SAE-5 flange belonging to a Technomarine (TwinDisc) TMC60E gearbox. I have drawings available for anyone who contemplates doing a similar job.
The bell housing also carries the starter motor on top of the gear box and serves as an engine support in combination with vulcanized rubber mounting pads.
The standard engine coupler disk available for this gearbox is far too small to fit the VW flywheel, but after totally dissecting the clutch parts the clutch cover car be used as an adapter. A special tools must be made first to properly align the engine coupler and drill 8 mounting holes.
The exhaust manifold and turbocharger were removed and replaced by a combined manifold/heat exchanger from Bowman U.K. This light alloy part was originally designed for the 1.5 ltr VW engine but also fits the larger models. Since the Bowman exhaust has the exit at the back of the engine and VW's manifold has the output flange between cyl. 2 and 3, the small Garrett turbocharger must move to a new location, which isn't as simple as it sounds.
I made an adapter with a 4 hole flange for the exhaust manifold and a 3 hole one for the turbocharger, the angle between them approx. 30 degrees. The oil feed tube can be reused after heating and bending it in the desired shape, but the oil return is too short and must be newly made. VW used an armoured hose with pressed on fittings, I made it from soft copper tube, soldered to the old flanges.
The Garrett turbocharger has a membrane operated waste gate and a fairly large cast iron exhaust gas chamber, which in the car was attached to some sort of ball joint on the exhaust pipe. I flexed off the two fingers that held the ball joint and used the lathe to create a smooth surface of nearly 2" to attach the exhaust hose later. Just above that area I drilled and threaded a 5/8" hole and made a stainless steel hose adapter for it, that connects to the raw water outlet of the Bowman manifold.
There is some doubt in my mind about this construction, because the turbocharger will be blowing very hot gas in a cast iron chamber that has a water cooled end. But I could not come up with a better solution: the exhaust hose would burn away within minutes if no water is injected at that point, and the shape of the turbocharger is far too complicated to cool the outside surface.
Now I am working on the next issue. Because the plumbing is totally different now, a lot of hoses are needed to connect the water pump intakes and cylinder head outlets, that are all on opposite sides of the engine. Normal hoses cannot be used because space is restricted and the engine would look like a pile of sausages, so I need to find automotive cooling hoses with molded bends at the required locations or cut them up in suitable pieces and reconnect them with steel or copper tube.
I am presently converting two small VW engines (1.9TD) for their marine future and come across various issues.
Every article I read about converting car engines points out that you should make sure the engine is in good condition, like no oil leaks, not much smoke, abnormal noises etc. But if you buy an engine from a recycling company, like I did, the part has been removed from the wrackage with crude tools like a flex and a bolt cutter. All wiring, bowden cables and hoses have been cut off, the oil has been drained and the exterior pressure cleaned. Just to start up the engine to check if it runs at all, requires the purchase of various items left in the car, like a glow plug relay, starter switch and basic wiring. Also a complete cooling system has to be built: with the 6 cut off hoses the engine was deliverd with, even a short test run might prove fatal.
For this specific engine, a further problem is, that in the VW Transporter the engine is attached to a combined bell housing/gear box that also holds the starter motor. That part is sold separately for approx. $400 but is unsuitable for a marine engine because a marine gearbox should be attached.
So I work on the assumption that the supplier is a decent guy until proven otherwise....
From 1/4" mild steel plate and some 1/2" pipe I have constructed a bell housing with a large hole that fits the SAE-5 flange belonging to a Technomarine (TwinDisc) TMC60E gearbox. I have drawings available for anyone who contemplates doing a similar job.
The bell housing also carries the starter motor on top of the gear box and serves as an engine support in combination with vulcanized rubber mounting pads.
The standard engine coupler disk available for this gearbox is far too small to fit the VW flywheel, but after totally dissecting the clutch parts the clutch cover car be used as an adapter. A special tools must be made first to properly align the engine coupler and drill 8 mounting holes.
The exhaust manifold and turbocharger were removed and replaced by a combined manifold/heat exchanger from Bowman U.K. This light alloy part was originally designed for the 1.5 ltr VW engine but also fits the larger models. Since the Bowman exhaust has the exit at the back of the engine and VW's manifold has the output flange between cyl. 2 and 3, the small Garrett turbocharger must move to a new location, which isn't as simple as it sounds.
I made an adapter with a 4 hole flange for the exhaust manifold and a 3 hole one for the turbocharger, the angle between them approx. 30 degrees. The oil feed tube can be reused after heating and bending it in the desired shape, but the oil return is too short and must be newly made. VW used an armoured hose with pressed on fittings, I made it from soft copper tube, soldered to the old flanges.
The Garrett turbocharger has a membrane operated waste gate and a fairly large cast iron exhaust gas chamber, which in the car was attached to some sort of ball joint on the exhaust pipe. I flexed off the two fingers that held the ball joint and used the lathe to create a smooth surface of nearly 2" to attach the exhaust hose later. Just above that area I drilled and threaded a 5/8" hole and made a stainless steel hose adapter for it, that connects to the raw water outlet of the Bowman manifold.
There is some doubt in my mind about this construction, because the turbocharger will be blowing very hot gas in a cast iron chamber that has a water cooled end. But I could not come up with a better solution: the exhaust hose would burn away within minutes if no water is injected at that point, and the shape of the turbocharger is far too complicated to cool the outside surface.
Now I am working on the next issue. Because the plumbing is totally different now, a lot of hoses are needed to connect the water pump intakes and cylinder head outlets, that are all on opposite sides of the engine. Normal hoses cannot be used because space is restricted and the engine would look like a pile of sausages, so I need to find automotive cooling hoses with molded bends at the required locations or cut them up in suitable pieces and reconnect them with steel or copper tube.