Engine losing power after running for an hour

[Stroudwater1]

This is a fairly consistent time though when it starts to slow down, wouldn’t diesel bug dirt be a problem from the set off ir be intermittent maybe ? 
 

it would help to see the water pump. It’s a pretty easy fix if it’s rubber impeller veins fitted that are a bit knackered (as long as veins aren’t in the system)! Someone I know changes their neoprene impeller annually. 

[Tony Brooks]

1 hour ago, Stroudwater1 said:

Someone I know changes their neoprene impeller annually. 

 

As is the normal recommendation.

 

 

 

 

[moiuk]

19 hours ago, magnetman said:

 

I think the hot fuel story could be relevant. Neutral and reverse seem to need less fuel in general and the OP did say things improve after everything is allowed to cool down. 

 

Injector lubrication is an interesting thing as it relies on the diesel. 

 

 

 

 

 

 

It does look like this problem is happening when the engine is being run under load. Its not an intermittent problem as it seems to happen reliably according to the temperature of the gearbox. The gearbox may not be too hot but the symptom IS related to engine load. 

 

 

 

 

I reckon it is overheating and the temperature gauge is bust. 

 

So I measured the temperature with an infrared monitor again today and the water going into the skin tank is showing 60 degrees (which matches the temperature gauge) and out of the skin tank is 30 degrees.

15 hours ago, Bee said:

Have you a tacho fitted? how many revs is it usually running at? The terrible old Perkins that gave me problems was OK until I needed a bit more shove (like going against a current) when the b****** would drop back to a fast tickover)  That was diesel bug and dirty fuel 

The revs monitor doesn't seem to be reliable (I think it st is sometimes) but when the problem occures the revs drop.

15 hours ago, Stroudwater1 said:

This is a fairly consistent time though when it starts to slow down, wouldn’t diesel bug dirt be a problem from the set off ir be intermittent maybe ? 
 

it would help to see the water pump. It’s a pretty easy fix if it’s rubber impeller veins fitted that are a bit knackered (as long as veins aren’t in the system)! Someone I know changes their neoprene impeller annually. 

Where is the water pump? Will that be on the back next to the alternator (assuming the belt that does the alternator also does the water pump? I can get a picture of that later if that is correct.

 

 

Untried something else yesterday/today which was to run the engine a little less hard and it made a difference in that the problem didn't occur until 2.5 hours of cruising instead of just over an hour when running it hard.  The problem still occured though although it was less drastic. I still had a reasonable amount of power but still significantly less than when I first get going with a cold engine.  Consistently the problem seems to occur when the gearbox measures above 65 degrees.

 

It seems repeatable for the problem to occur with how hard I run it/length of run time which indicates to me that it is a temperature issue ??  Any thoughts on this? Could fuel bug still be the culprit if it is consistent with time/how hard I run it?

 

The large circular plate behind the gearbox (not sure what this is if you can advise) measures at just over 60 degrees which seems to match the water temperature so guessing this is also normal ?

[Tony Brooks]

18 minutes ago, moiuk said:

Where is the water pump? Will that be on the back next to the alternator (assuming the belt that does the alternator also does the water pump? I can get a picture of that later if that is correct.

 

The ENGINE water pump (as opposed to Jabsco type pump) will have a pulley that is driven by the alternator belt, the belt then goes down to the engine crank shaft pulley and back up to the alternator. Given the temperatures you have just quoted, that are more or less as expected, the chances of a faulty water pump are only a little above zero. On your engine, the water pump impeller is almost certainly cast iron. Very, very occasionally cast iron impellers fall off the shaft, but if yours had done that, the engine would boil within a very few minutes of starting. The pump will be on the FRONT of the engine, not the back. The gearbox is on the back.

 

If you decide to look at the impeller, you will probably need new antifreeze and a new pump gasket.

 

How many times have you been told the fuel system is suspect and bug is a good candidate. Until you drain the bottom of the tank, inspect what the water trap has caught, cleaned the gauze in the top of the lift pump and change & inspect the fuel filter element, you can not rule this out. Draining the bottom of the tank is, in my view, many times easier than taking the engine water pump off.

 

PS, your rev counter might be driven by a cable from the engine using a thing like a car speedometer cable, but it is just as likely to be driven from the W terminal or a phase tap on the alternator. make sure the terminal on W is clean and tight. A faulty alternator will cause rev counter problems, even though many will think the alternator is still charging properly (it won't be). This also raises questions bout the alternator belt condition and tightness.

Edited August 31, 2023 by Tony Brooks

[Bee]

If this engine was still in its original home, a van or something like that and it was giving this trouble then the garage that you took it too would start by suspecting dirty fuel

[moiuk]

6 minutes ago, Bee said:

If this engine was still in its original home, a van or something like that and it was giving this trouble then the garage that you took it too would start by suspecting dirty fuel

 

Thank you. This certainly needs to be checked now then as many have suggested already. My faulty thinking and understanding has (incorrectly) asssumed that due to the correlation with temperature and how hard I'm running it that fuel was a low probability, but those that know better than me keep suggesting fuel so I wil need to get this checked next.

 

 

23 minutes ago, Tony Brooks said:

 

How many times have you been told the fuel system is suspect and bug is a good candidate. Until you drain the bottom of the tank, inspect what the water trap has caught, cleaned the gauze in the top of the lift pump and change & inspect the fuel filter element, you can not rule this out. Draining the bottom of the tank is, in my view, many times easier than taking the engine water pump off.

 

PS, your rev counter might be driven by a cable from the engine using a thing like a car speedometer cable, but it is just as likely to be driven from the W terminal or a phase tap on the alternator. make sure the terminal on W is clean and tight. A faulty alternator will cause rev counter problems, even though many will think the alternator is still charging properly (it won't be). This also raises questions bout the alternator belt condition and tightness.

 

Thank you.

 

I will do the fuel inspections. Not done these before so will need to work out where they all are and how to do it. Will be simple after I have done it once. The fuel filter is probably due a change regardless.

 

I'll check the rev counter connections. I have a separate ammeter measuring the alternator charging which looks to be charging correctly. I checked the alternator belt when I changed oil last week and looked to be fine.

[Tony Brooks]

51 minutes ago, moiuk said:

I will do the fuel inspections. Not done these before so will need to work out where they all are and how to do it. Will be simple after I have done it once. The fuel filter is probably due a change regardless.

 

First, deal with whatever is in the bottom of the tank because once you have a length of hose and some milk cartons it is very easy to do with a typical narrow boat tank.

 

Lest see if this helps. I have shrunk your photos a bit, but you should still see the important bits.

 

The easiest first check is to see what is in the water trap. This image shows what I think is your water and the fuel filter.

 

 

At the bottom of the water trap is a tap, as shown in this photo:

 

 

As long as the fuel level in the tank is higher than the tap then put a carton or something under the tap and undo it. Whatever is in the water trap should trickle out, but you may have to take the tap right out and prod the hole. If you have trouble putting the ta back in then turn off the main fuel tap (should be marked as per the BSS), fit the tap but leave loose, turn on fuel and a sit leaks out tighten the tap. Try not to do this because it may then involve bleeding the system.

 

Back to the first diagram.

 

The fuel filter looks as if it is a standard CAV 296 type unit, so it consists of three parts, the head/top, the actual changeable element, and the sediment bowl. You will see a hexagon bolt head right in the centre of the head, about 1/2" AF or 11mm. If you undo this, the two parts will come off the head. It may need a geed twist to free the parts from the rubber seals.  Any decent motor factors should sell the 296 element. The placing of the 3 or 4 O rings is critical, so for your first attempt my advice would be to leave them all in place and refit with the old ones. If you do remove the seals ensure the new ones go back in the correct place.

 

If you change the filter, you will definitely have to bleed the fuel system, so if you don't know how to do this you may be better to pay a professional.

 

Now the lift pump.

 

I think that it will look like this:

 

 

 

It will be about halfway down the engine cylinder block, probably on the same side as the filter, but don't hold me to that. One of the pipes will go to the fuel filter and the other typically comes from the water trap.

 

Not the single bolt in the top of the domed cover. If you undo that, it will normally expose a brass or plastic gauze above a sediment trap. There is a rubber O ring that fits into the cover. On no account remove this. They tend to swell, so you can never get it back in. The gauze needs cleaning and the sediment trap needs cleaning out. be aware that doing this will require the system to be bled.

 

If you have never bled the engine, then maybe pay a professional to change the filter and clean the lift pump gauze. If the tank fuel level is below the water trap, get the professional to do that as well. Make sure that you are present to see what is done and collect fuel samples from each item and take photos so was can advise on what is fund. It may be better to limp back to your home mooring where you presumably have contacts for such work.

 

 

[magnetman]

My Perkins P4 has some sort of bizarre vacuum operated throttle system. There is a butterfly valve in the air intake. 

 

I don't know if the 108 has this setup. @Tony Brooks will know.

 

If it does is there a possibility there is something going on with the vacuum pipes? 

 

 

Another thing which needs to be established is does the engine start to smoke excessively when the power loss occurs? If there is sudden appearance of black smoke this would indicate engine overloading. 

 

I've got an unproven idea that one can also detect fuel dirt or bug problems from the smell of the exhaust. 

 

Ears eyes and nose can be very useful sensors. 

 

 

 

 

[moiuk]

7 minutes ago, Tony Brooks said:

 

First, deal with whatever is in the bottom of the tank because once you have a length of hose and some milk cartons it is very easy to do with a typical narrow boat tank.

 

Lest see if this helps. I have shrunk your photos a bit, but you should still see the important bits.

 

The easiest first check is to see what is in the water trap. This image shows what I think is your water and the fuel filter.

 

 

At the bottom of the water trap is a tap, as shown in this photo:

 

 

As long as the fuel level in the tank is higher than the tap then put a carton or something under the tap and undo it. Whatever is in the water trap should trickle out, but you may have to take the tap right out and prod the hole. If you have trouble putting the ta back in then turn off the main fuel tap (should be marked as per the BSS), fit the tap but leave loose, turn on fuel and a sit leaks out tighten the tap. Try not to do this because it may then involve bleeding the system.

 

Back to the first diagram.

 

The fuel filter looks as if it is a standard CAV 296 type unit, so it consists of three parts, the head/top, the actual changeable element, and the sediment bowl. You will see a hexagon bolt head right in the centre of the head, about 1/2" AF or 11mm. If you undo this, the two parts will come off the head. It may need a geed twist to free the parts from the rubber seals.  Any decent motor factors should sell the 296 element. The placing of the 3 or 4 O rings is critical, so for your first attempt my advice would be to leave them all in place and refit with the old ones. If you do remove the seals ensure the new ones go back in the correct place.

 

If you change the filter, you will definitely have to bleed the fuel system, so if you don't know how to do this you may be better to pay a professional.

 

Now the lift pump.

 

I think that it will look like this:

 

 

 

It will be about halfway down the engine cylinder block, probably on the same side as the filter, but don't hold me to that. One of the pipes will go to the fuel filter and the other typically comes from the water trap.

 

Not the single bolt in the top of the domed cover. If you undo that, it will normally expose a brass or plastic gauze above a sediment trap. There is a rubber O ring that fits into the cover. On no account remove this. They tend to swell, so you can never get it back in. The gauze needs cleaning and the sediment trap needs cleaning out. be aware that doing this will require the system to be bled.

 

If you have never bled the engine, then maybe pay a professional to change the filter and clean the lift pump gauze. If the tank fuel level is below the water trap, get the professional to do that as well. Make sure that you are present to see what is done and collect fuel samples from each item and take photos so was can advise on what is fund. It may be better to limp back to your home mooring where you presumably have contacts for such work.

 

 

Wow that is sooo helpful. Thank you.

 

I think I will find an engineer in London when I am off the river and watch/learn as he does it.

 

3 minutes ago, magnetman said:

My Perkins P4 has some sort of bizarre vacuum operated throttle system. There is a butterfly valve in the air intake. 

 

I don't know if the 108 has this setup. @Tony Brooks will know.

 

If it does is there a possibility there is something going on with the vacuum pipes? 

 

 

Another thing which needs to be established is does the engine start to smoke excessively when the power loss occurs? If there is sudden appearance of black smoke this would indicate engine overloading. 

 

I've got an unproven idea that one can also detect fuel dirt or bug problems from the smell of the exhaust. 

 

Ears eyes and nose can be very useful sensors. 

 

 

 

 

 

No significant increase in the exhaust smoke when it happens.

[Tony Brooks]

Just now, magnetman said:

My Perkins P4 has some sort of bizarre vacuum operated throttle system. There is a butterfly valve in the air intake. 

 

I don't know if the 108 has this setup. @Tony Brooks will know.

 

If it does is there a possibility there is something going on with the vacuum pipes? 

 

 

Another thing which needs to be established is does the engine start to smoke excessively when the power loss occurs? If there is sudden appearance of black smoke this would indicate engine overloading. 

 

I've got an unproven idea that one can also detect fuel dirt or bug problems from the smell of the exhaust. 

 

Ears eyes and nose can be very useful sensors. 

 

 

 

 

 

No, it does not have a throttle butterfly and vacuum pipe. Even if it did and the pipe leaked, all that would be likely to happen is the engine go to full revs with no control. It has a totally different injection pump. Basically, it uses the same system as the small BMC diesels.

 

I don't think that you can detect the presence of bug by exhaust smell because basically it causes fuel starvation.

[john.k]

No,the P4 has a straight vacuum governed BPE type inline pump......an excellent pump from pre war days .............the 4/108 has a DPA pump ,either hydraulically or mechanically governed.

[magnetman]

Just now, Tony Brooks said:

 

 

 

I don't think that you can detect the presence of bug by exhaust smell because basically it causes fuel starvation.

My exhaust smells different when the tank is very low. This probably isn't bug as have never had any problems but the smell does change. 

 

I put it down to the fuel being less clean further down the tank and I'm sure even with good filters some dirt is getting through to the high pressure side. 

 

 

 

 

[Tony Brooks]

1 minute ago, moiuk said:

Wow that is sooo helpful. Thank you.

 

I think I will find an engineer in London when I am off the river and watch/learn as he does it.

 

 

Good luck with finding an engineer in London. I understand the London Boaters Facebook page is where you get recommendations. There is/was a yard at Laleham that seems to have a load of narrowboats around most of the time. You may pass them on your way downstream.

 

Hhaev you found my website with the hopefully useful notes yet? Free for you to download and print. tb-tarining.co.uk. Look at the BT fuel system notes as well.

 

 

[john.k]

Very simple way to fix bug is dump a bottle of boat  fuel biocide into the tank..............according to the label,this chemical reverses the osmotic gradient between the bacterial /fungal cells and the water ,and causes the cells to burst ,therby neutralizing the bug as long as the fuel contains biocide.............This stuff is extremely effective ,reducing the snotty sludge to powder ,and curing fuel blockage completely ..................and at the crime of repeating myself .......put some decent filters on your boat.

Edited August 31, 2023 by john.k

[magnetman]

The yard at Laleham is 4allmarine. 

 

Not used their services myself so unable to recommend but they do a lot of steel boat work. Proper boatyard not some fancy marina. 

 

Not that a Perkins 4108 is a steel boat engine. 

 

Another yard who know an awful lot about this engine will be Chertsey Meads marine. Proper boatyard not some fancy marina..

 

There is also Adam AJ Marine at Bell Weir he knows his business. 

 

 

Proper boatyard not some fancy marina..

 

 

Can you tell I'm not a fan of fancy marinas ? 

[Tony Brooks]

1 minute ago, magnetman said:

Not that a Perkins 4108 is a steel boat engine. 

 

Along with he 4-107 probably as poplar as the BMCs in GRP cruisers, so all the yards you mention should be familiar with the engine. I suspect more so that on the canals where Lister and BMC seemed to the go to engines.

[magnetman]

Chertsey Meads Marine I think probably the most knowledgeable. They have a large heap of old perkins and BMC engines in the boatyard. Loads of them. 

 

A bit awkward to get on there with a narrow boat so phoning ahead is probably wise. 

 

Not been down there this yar myself and the story was it is two brothers one who wants to sell the land for housing (it has houses each side) and the other likes the boatyard. 

 

Could disappear at any moment as it is an outrageously valuable site. 

 

Good vibe there I like that yard. Long may they continue to do boat things. 

 

 

 

 

 

 

 

 

I suppose I am a bit biased as flooded the engine bay on my first narrow boat on the second day due to a weedhatch fault and stopped near there. 

 

Walked round to the boatyard explaining the gearbox was making a terrible noise and had water in it they sold me a bottle of EP90 gear oil (Lister manual gearbox (rather than doing me over). 

 

This was 1994 and I believe the thing is still working. 

 

Some yards could have taken advantage. They didn't. 

 

Another time I had a shredded alternator belt and the bloke sold me a new belt AND reminded me to ensure the alternator was lined up properly. Turned out it was slightly out of alignment so I moved it a bit and it sorted it out. I had previously replaced a belt but put the alternator back on slightly wrong. 

 

So instead of getting the boat in and making profit they help you. 

 

I like this. 

 

 

 

 

[moiuk]

An update to this topic/issue..

 

Not been crusing very much after I got off the Thames as well as holidays etc.

 

However, I have now managed to Syphon off some fuel into a glass bottle to see how it looks (photo attached). I will leave it for a week or two and compare.

 

 

Not sure what I am looking at, so opinions if this looks normal would be appreciated.

 

I still need to locate an engineer to help do a service on the fuel line/filter etc. Chertsey meads marina sounded perfect after I spoke to them, but I was unable to stop as I went past at a time when they were free, so that job still needs doing.

 

Considering learning how to prime it and do the job myself.

[Alan de Enfield]

Is that a sample taken from the bottom of your tank ?

 

 

Well, if my experience is anything to go by you have 99% water topped by 1% diesel (Diesel is the darker colour and floats on the water)

 

The red dye seems to discolour the water with an orange tint.

 

Here is my sample :

 

 

 

 

[moiuk]

Doesn't sound good!

 

Okay, my water trap is below my tank, so I'm gonna bleed that and see what comes out..

5 minutes ago, Alan de Enfield said:

Is that a sample taken from the bottom of your tank ?

 

 

Well, if my experience is anything to go by you have 99% water topped by 1% diesel (Diesel is the darker colour and floats on the water)

 

The red dye seems to discolour the water with an orange tint.

 

Here is my sample :

 

 

 

 

I syphoned it out from the tank by putting a hose in from the top. I got the hose down as far as I could.. 

 

The tank is down to about 50 litres because I didn't want to fill up before fixing this issue..

[Tracy D'arth]

You have a heavy fuel contamination with water. The fuel filters will be wet with water and will not pass fuel properly hence you get fuel starvation. You need to drain the fuel tank completely, settle or polish the fuel or replace with new, and change all the filters after you have bled the fuel lines very well to get all the contaminated fuel out of the lines and the engine.

[moiuk]

Thanks.  I will Syphon all the fuel out.

 

Is it okay to just let the fuel.settle and then Syphon the diesel off the top and put that back, or is it going to be better to just dispose of everything and replace with fresh?

 

Is this likely to have done any lasting damage to.the engine?

[Jen-in-Wellies]

For the future, how is the water getting in the tank? Do you have one of those flush fit fuel caps with an o-ring seal? What about the tank vent? Hopefully stop it happening again.

[Tracy D'arth]

If it settles out properly it will be OK. May take several days to settle.

Unlikely to do any damage but don't delay in sorting it. Some injection pumps have steel springs in and these will rust if left with water in. From experience, Mitsubishi/Vetus for instance would suffer in this respect.

The old CAV pumps on Perkins will be more tolerant but its not good for them.

Edited October 5, 2023 by Tracy D'arth

[moiuk]

Yes it's is a flush fit fuel cap type, although I can't see how a significant amount of water could enter. I'm thinking that condensation is a likely culprit. In winter I keep the boat pretty warm and in the engine bay I get significant condensation on the outside of the skin tank which collects a good amount of water in the bilge that I need to pump out. If the same is happening on the inside of the fuel tank then that would be a good amount of water.

 

I intend to keep the tank full over this winter, but any other suggestions if this doesn't sound right would be helpful.

3 minutes ago, Tracy D'arth said:

If it settles out properly it will be OK. May take several days to settle.

Unlikely to do any damage but don't delay in sorting it. Some injection pumps have steel springs in and these will rust if left with water in. From experience, Mitsubishi/Vetus for instance would suffer in this respect.

The old CAV pumps on Perkins will be more tolerant but its not good for them.

 

Thanks.  I think I have found a few 25l containers so will get this done asap.

 

My thinking is that once I have new fuel in the tank, to run the engine to clear the bad fuel through and then replace the fuel filter and drain the water trap.

 

Does this sound a reasonable approach?