Bukh DV8 oil in water problem

[Hoxans]

Hi we have a DV 8 sail drive that was run without water

Overheated - still runs but low on power - no new engine noises, however has low compression

Oil in water - when it is running if you remove oil dip stick oil/water spurts out
The questions I have are
1. The water in the crankcase - could this be getting into the bottom end from a blown head gasket/warped head or some other cause?
2. How difficult is it to remove the cylinder head while it is still in the boat

 

[VicS]

Hi we have a DV 8 sail drive that was run without water

Overheated - still runs but low on power - no new engine noises, however has low compression

Oil in water - when it is running if you remove oil dip stick oil/water spurts out
The questions I have are
1. The water in the crankcase - could this be getting into the bottom end from a blown head gasket/warped head or some other cause?
2. How difficult is it to remove the cylinder head while it is still in the boat

I would go for the head gasket as the most likely cause of the trouble but a damaged head could be possible so that must be checked also.

Fairly straightforward job to remove the head provided access is good enough

There is a workshop manual at http://www.motoren.ath.cx/Download.php?filename=/bukh/Bukh_DV8LSME_Manual.pdf or http://www.bluemoment.com/manuals/Bukh_DV8LSME_Manual.pdf but it does not look all that helpful

 

[Hoxans]

Hi Vic
Thanks for getting back to the forum and your suggestions and manuals
Any additional thoughts re the cause of the water/ oil spurting from the oil stick tube when the engine is running
Regards
David

 

[RichardS]

Hi Vic
Thanks for getting back to the forum and your suggestions and manuals
Any additional thoughts re the cause of the water/ oil spurting from the oil stick tube when the engine is running
Regards
David

It's not unusual to have a crankcase which is slightly above atmospheric pressure but a leaking head gasket will certainly make this worse so don't be surprised if some spray comes out when the engine is running. Normally it would be just oil spray of course.

Richard

 

[vyv_cox]

I assume the engine was run with the coolant supply closed or blocked? The first point is that seawater in the engine must be removed ASAP. It will cause considerable damage inside the engine, especially to crankshaft bearings but also to all steel and iron components. I would check the water pump early on, as failure of this item is a major source of water in the crankcase of Bukh engines. It is quite difficult to understand how much water could enter the engine in a seawater cooled installation, the pressures don't really add up as they do with an indirectly cooled one. Which doesn't mean that the head is not warped or cracked, just that there may be more than one consequence of running dry.

 

[Hoxans]

---------- Forwarded message ----------
From: David Boyd <hoxans@gmail.com>
Date: Sunday, 17 January 2016
Subject: Bukh reply to vyv
To: David Boyd <hoxans@gmail.com>


Hi vyv
Yes the sea water inlet was closed, which is why it overheated
Thanks for your comments - are you saying the water pump may have been damaged by being run dry and is now leaking somehow? and putting salt water into the sump?
The engine cooling system still works (after installing a new impeller) - water is coming out the rear of the boat as per the way it used to before the incident
Okay we need to take the head off, have it checked/shaved plus we should look at the water pump for damage - are there any tell tale signs to indicate a problem with the water pump?
Finally is there a way of checking if we have damage to the engine bearings from the salt water

Best regards
David

 

[vyv_cox]

---------- Forwarded message ----------
From: David Boyd <hoxans@gmail.com>
Date: Sunday, 17 January 2016
Subject: Bukh reply to vyv
To: David Boyd <hoxans@gmail.com>


Hi vyv
Yes the sea water inlet was closed, which is why it overheated
Thanks for your comments - are you saying the water pump may have been damaged by being run dry and is now leaking somehow? and putting salt water into the sump?
The engine cooling system still works (after installing a new impeller) - water is coming out the rear of the boat as per the way it used to before the incident
Okay we need to take the head off, have it checked/shaved plus we should look at the water pump for damage - are there any tell tale signs to indicate a problem with the water pump?
Finally is there a way of checking if we have damage to the engine bearings from the salt water

Best regards
David

Look on my website under engines for some examples. Yes, if the engine was run for sufficient time for the seals to be affected by frictional heat you may well be getting seawater past them into the engine. Water that passes the first seal should emerge from the tell-tale hole but the ones on Bukh engines are often very small and they become blocked by grease and debris.

You cannot inspect the bearings without dismantling, quite a major job on the Bukhs. But you should change the oil ASAP after getting it good and hot.

 

[Hoxans]

Hi VYV
Thanks for your reply - much appreciated
A question about removing and reinstalling the head on the DV8 - the manual says there are 4 nuts to be undone to take the head off
When we put the head back on do we have do some valve timing - to avoid one of the valves going through the piston
Best regards
David

 

[stevd]

You dont need to worry about the timing removing the head, as the valves are push rod operated from the cam. I would check the valve clearances after removal though.

There is a good chance the water is getting passed a blown head gasket or warped head, but I would recommend as Vyv has suggested to inspect the water pump before the removal of the head. Whilst removing the head is an easy job, the cost of a new BUKH head gasket is expensive. I would inspect the water pump seals first to rule that out.

Is it difficult to start?

 

[VicS]

Hi VYV
Thanks for your reply - much appreciated
A question about removing and reinstalling the head on the DV8 - the manual says there are 4 nuts to be undone to take the head off
When we put the head back on do we have do some valve timing - to avoid one of the valves going through the piston
Best regards
David

As stevd pointed out it will be the valve clearances that will need to checked and adjusted after refitting the head.

If no other work is necessary other than replacing the gasket then the amount of adjustment needed should be relatively small

If the head is distorted and has to be skimmed then ITYWF that it will need a special, thicker, gasket to compensate for the material removed in the machining process.

Whether you only need to renew the gasket or if the head requires attention be sure that all components are refitted in their original positions. There is a note in the manual referring to refitting the pushrods in their original positions! Maybe they are the only bits that can be fitted wrongly.

stevd suggests checking the water pump seals first. It'sensible to do that but since you report low compression and low power etc I'd say the head gasket has certainly gone, if nothing worse. Clearly there are more problems than just water in the oil.

 

[Hoxans]

Hi Stevd
Thanks for your input - I am pretty sure we have a problem with the head/head gasket as the engine now has low compression (after running hot) and it has also lost power
We will definetly remove the water pump first
So when we reinstall the head it doesn't matter if the engine has moved half a turn, just check the valve clearance
Best regards
David

 

[RichardS]

Hi Stevd
Thanks for your input - I am pretty sure we have a problem with the head/head gasket as the engine now has low compression (after running hot) and it has also lost power
We will definetly remove the water pump first
So when we reinstall the head it doesn't matter if the engine has moved half a turn, just check the valve clearance
Best regards
David

Once you have re-assembled everything you will have to turn the engine to TDC with a spanner on the crankshaft to set the valve clearances so it doesn't matter whether the crankshaft is turned or not whilst the head is off. However, take care not to start the engine until you have checked the clearances.

Richard

 

[VicS]

Once you have re-assembled everything you will have to turn the engine to TDC with a spanner on the crankshaft to set the valve clearances so it doesn't matter whether the crankshaft is turned or not whilst the head is off. However, take care not to start the engine until you have checked the clearances.

Richard

Just to add, because there is no info on the procedure for checking valve clearances in the manual, that's TDC when both valves are fully closed at the end of the compression stroke/ start of the power stroke , not TDC when the valves are rocking between exhaust valve open and inlet valve open.