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MC42 Fuel Filter help & Rocker Cover Gasket needed


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Good afternoon,

 

1.  Can anyone please talk me through changing a fuel filter on my Perkins MC42, I've never done it before and its long overdue.

I'm scared of getting air in it, but I'm told its fairly easy if you follow the correct procedure.

 

The current fuel filter is an Motaquip VFF285 which I'm finding hard to cross reference, I bought a Perkins filter from parts4engines ( https://www.parts4engines.com/perkins-perama-mc42-fuel-filter/ ) hoping this is correct replacement

 

2. I have an oil leak from my Rocker Cover, I have tried tightening it but its not helped, possible made it worse....
Does anyone have a parts number for the Rocker Cover Gasket or know where I could buy one? having no luck locating one online

 

I'm trying to give my engine a good service and paint (which is how I discover the oil leak) so any help you can give me would be much appreciated.

 

Many thanks!

 

See below for my fuel system/filter setup

 

 

20200928_154557_HDR.jpg.329534fb62aa4d136377b8a6a8ecdd24.jpg

 

20201019_152447.jpg.333ab3532a9787a9aaca69da93c087f3.jpg     20201019_152633_HDR.jpg.c9e393be762776ef6b8b8febca8d9534.jpg

 

 

20201019_152503.jpg.db75230b4089824d89b50e2903aae8e3.jpg

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Apologies for the double post,

 

I've been doing some investigating and if anyone in the know can answer these questions that would be helpful

 

In this photo the fuel goes into something directly from the fuel tank, I'm guessing its a separator?  

if so do I take that apart?   on the right above the blue

20201019_215723.jpg.bae4dac56d746dffca7ea89d79b06925.jpg

 

And then from the silver cylinder (separator?) into this image below with the red arrow.

Is that the pump for clearing air out of the fuel? is it finger operated?     
(also missed a bit of the painting underneath...)

 

original_3ace958a-729b-41a7-a79b-e83108d3b9d9_20201019_220152.jpg.83e69ec8d3aad7ad0a3d0e2548bb63d4.jpg

 

So my thinking is, after you have changed the fuel filter you can pump the fuel in till there are no spurts of air and its just fuel.

 

Again, many thanks to whomever can sit down and answer some of my fairly basic questions... 

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I used to have an MC42, for about 23 years until I wore it out 5 years ago, so will try and remember.

 

The silver thing may be a water separator, or may contain a filter. I don't think you can tell without taking it apart; mine had a water trap which was a plastic cone inside there and was a slightly different design so I may get the details wrong here. I'll refer to it as a separator for convenience. If you are lucky perhaps someone will recognise it and come through with further details.

 

Yes the small lever you have highlighted is a manual operator to the lift pump, so yes you use your finger on it.

 

The blue-painted nut on top of the filter, and the small turn-screw on top of the separator, are both there to allow you to remove air from the system.

 

The procedure is simple. First, turn off the diesel at the red tap on the pipe from the tank. Next, I would open the air bolt on the fue filter by a couple of turns (not a lot should come out, depending on the exact position of the lift pump when the engine stopped; you are only doing this to let the air in at the moment, but it may be worth having a cloth around or a bowl/jug underneath just in case). Now place a container (bowl or jug) under the separator, and open the drain underneath it. This is usually a turnscrew like the one on the top but may be a bolt. Some diesel will come out. When it stops dripping, open the air screw at the top, some more diesel will probably come out. Have a look, does it contain water, or muck? Here it is a bit vague, ideally you would open up the separator to check whether or not it contains a filter, but if you do so you will need a new filter element for it (not available from Perkins, it's nothing to do with them) and new rubber gaskets; if it only contains a separator, however, you don't need to do anything else. My guess is that you have just a separator there, but that is a guess; let's assume that to be the case. If so, simply re-tighten that drain screw; don't forget that part or it gets very messy.

 

Now you can change the filter element itself (do you have a strap wrench?); start by putting a container underneath it, then just unscrew it (it will be full of diesel, which you can pour into your jug/bowl though if you are a butterfingers like me you might drop the whole lot! Make absolutely certain that the rubber washer has come off with the old filter.

Screw the new filter into place, and you are almost there. Turn on the diesel at the tank, and watch until some starts to dribble out of the top of the separator (a cloth there may catch the inevitable overflow), then close that screw. Hopefully there is now no air in there, so you can start pumping with the lift-pump lever. After a while (maybe 20 pumps or so IIRC) you should see some diesel start to come out around the bleed nut, which you now close.

 

There shouldn't be much air in the system, but there is almost certain to be a little bit. Luckily the MC42 is self-bleeding, so at this point open the throttle to at least half-way and turn the starter. It should catch fairly quickly, but may then falter and die - don't panic, that just means you have used the fuel in the injector pipes and now have a bit of air to expel. If necessary, keep turning on the starter (always pause after 10 seconds to let things cool down) and it should start pretty easily. Check that nothing is leaking, and if all is OK you are done.

 

Finally look at the fuel you have collected in your jug/bowl. If it is clean and clear, you can safely pour it back into the tank; otherwise dispose of it.

 

Regarding your gasket, if you are certain that it is a gasket problem, it may just be worth contacting Jonathan at UCC - he may know of a source of supply as their hire-fleet used to all have MC42's. Where does the oil actually appear?

 

Hope this helps

 

 

Edited by Keeping Up
Added comment to expect maybe a small amount of diesel from the top bleed screw
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Hi Keeping Up - thank you for all that, info the detail is very helpful! I feel a lot more confident about doing it now, it confirmed a lot of things. 
I will have to investigate the "separator"..

 

The oil had gone down the side of the engine at a few points from the rocker cover, only a small leak but noticeable especially on new paint. 

I guess I don't know if it is the gasket 100% but its definitely coming from that join all around.

 

Ex Brummie - yes I think you are right, I has got worse since I tightened it so I should try loosen it off. Although I did tighten it to get rid of the leak in the first place. 

Interesting I had assumed it was under pressure. It was leaking and I havent touched it in years so there is something not right there, my only thought is it could be the gasket. 
 

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Yes it does sound as if you have a leak from the gasket. I asked where the leak was positioned, because it is quite common for there to be an oil leak where the feed pipe enters the front of the engine (below the pressure sensor), and it can easily be confused with a gasket leak there. The cure for that one is not quite what you would expect because the pipe joint there is rather unusual.

 

As an aside, although I would doubt if it would be causing your leak, it IS possible to have pressure inside the rocker cover. If the piston rings are worn, the pressure from the cylinders escapes into the crank-case and thence up into the rocker area. There would normally then be a short pipe to release that pressure into the air filter so that the oily fumes are consumed by the engine. This can get blocked, by a kink in the pipe or a build-up of sludge, and hence cause pressure in the rocker area. I can't see it in your pictures, and mine was a "low-profile" version of the engine in which the air filter was positioned lower down on the other side of the engine; so on mine the breather pipe went from the rocker cover, above the injectors, into the underside of the air filter.

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Thanks Keeping Up & Tony,

 

I have bought parts from diperk using my engine serial number, very helpful I recommend them. 
Thanks for your advice I will check what you have suggested.

 

I'm still looking for anyone who know what this is coming off the diesel feed, if not I will investigate when I get my parts

Assuming its a separator (the right black pipe has nothing to do with it)

2.jpg.62381c1759094ce639b32f98ff9e9b04.jpg

 

Thanks!

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1 minute ago, Boat_Around_Si said:

Thanks Keeping Up & Tony,

 

I have bought parts from diperk using my engine serial number, very helpful I recommend them. 
Thanks for your advice I will check what you have suggested.

 

I'm still looking for anyone who know what this is coming off the diesel feed, if not I will investigate when I get my parts

Assuming its a separator (the right black pipe has nothing to do with it)

2.jpg.62381c1759094ce639b32f98ff9e9b04.jpg

 

Thanks!

It is but what is inside is anybodies guess unless they recognise it and know. It may be a sedimentor (uses an inverted cone and a vortex to separate water and crud from the fuel) or it may be an agglomerator (uses a filter to agglomerate small water droplets into large ones that fall to the bottom).

 

It looks to me as if the bowl will drop off if you undo three or four screws/bolts but turn the fuel off first. If you do that try bleeding it when the fuel is back on via the finger screw in the top, otherwise it takes time but you can bleed any air in it as part of normal engine bleeding. If its a plain bowl fill it with CLEAN fuel before you refit it.

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4 minutes ago, Boat_Around_Si said:

Thanks Keeping Up & Tony,

 

I have bought parts from diperk using my engine serial number, very helpful I recommend them. 
Thanks for your advice I will check what you have suggested.

 

I'm still looking for anyone who know what this is coming off the diesel feed, if not I will investigate when I get my parts

Assuming its a separator (the right black pipe has nothing to do with it)

2.jpg.62381c1759094ce639b32f98ff9e9b04.jpg

 

Thanks!

It looks like an early CAV water trap, often called an agrommalator or sedimenter, there will not be  a filter inside. There will be a drain tap on the bottom to drain out water, check it regularly to prevent getting water into your fuel filter down stream.

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2 minutes ago, Tracy D'arth said:

It looks like an early CAV water trap, often called an agrommalator or sedimenter, there will not be  a filter inside. There will be a drain tap on the bottom to drain out water, check it regularly to prevent getting water into your fuel filter down stream.

Agglomerators do have some kind of filter inside that will not let water dropltes through the pours in the screen material.

 

Sedimentors are different and use an inverted cone to create a vortex in the fuel.

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8 minutes ago, Tony Brooks said:

Agglomerators do have some kind of filter inside that will not let water dropltes through the pours in the screen material.

 

Sedimentors are different and use an inverted cone to create a vortex in the fuel.

I sit corrected.  Pray what is a dropite?  As bad as my predictive text!  

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  • 2 months later...

Hi All -

A big thank you everyone for your help! esp Keeping Up - fuel filter changed and rocker cover gasket changed sucessfully.
Hopefully this thread will be helpful for other in the future.

 

As I have a few knowledgable Perkins people here...

I'm getting no reading on the engine temperature gauge up top.

Using the voltmeter I'm getting readings of 12.7v and 7.2v up top at the a gauge and the wires down by the sensor are around 5.3v.

 

Does the sensor require 6v to work? (I'm guessing it doesn't need 12v..)

It looks pretty old, quite rusty, if its the likely culprit I will replace it, or should I look at any other areas first?
See attached photo - again, very grateful or any help or ideas!
 

20210118_125634_2.jpg

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5 minutes ago, Boat_Around_Si said:

Hi All -

A big thank you everyone for your help! esp Keeping Up - fuel filter changed and rocker cover gasket changed sucessfully.
Hopefully this thread will be helpful for other in the future.

 

As I have a few knowledgable Perkins people here...

I'm getting no reading on the engine temperature gauge up top.

Using the voltmeter I'm getting readings of 12.7v and 7.2v up top at the a gauge and the wires down by the sensor are around 5.3v.

 

Does the sensor require 6v to work? (I'm guessing it doesn't need 12v..)

It looks pretty old, quite rusty, if its the likely culprit I will replace it, or should I look at any other areas first?
See attached photo - again, very grateful or any help or ideas!
 

20210118_125634_2.jpg

The sender wire is hanging out, needs a new crimp properly crimped so that the insulation is held too.

 

Short the lead on the sender to the engine, gauge should read full scale - hot.  Disconnected wire, gauge should not move. If both is so, you need a new sender.

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Thank you for the reply Tracy D'arth,

Can you please be more detailed? Do you meant take top connection from the sensor and connect it directly onto the engine? 

If you could spell it out in layman's terms it would be much appreciated ...

 

Thank you!      (I will re-crimp that wire with a new connecter when I've got down to the problem, thanks)

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34 minutes ago, Boat_Around_Si said:

Thank you for the reply Tracy D'arth,

Can you please be more detailed? Do you meant take top connection from the sensor and connect it directly onto the engine? 

If you could spell it out in layman's terms it would be much appreciated ...

 

Thank you!      (I will re-crimp that wire with a new connecter when I've got down to the problem, thanks)

Correct, just hold the connector  on a clean bare bit of the engine, with the ignition on,  the gauge should read hot. Only 12v, so no shocks!

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3 minutes ago, Boat_Around_Si said:

Hi Tracy D'arth,

 

Thanks for clarifying, I did as you suggest - the dial didn't move but the alarm behind the panel went off. 

So it must be sensing that it went straight to hot - guess that means the dial has a problem?

 

 

Are there two wire on that sensor?

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I may be wrong, it's a few years ago now, but aren't there 2 separate sensors on the engine, a variable one to drive the dial and a switch to drive the alarm. If so, and transferring the wire from the sensor to ground operates the alarm, perhaps the two have merely been swapped over?

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Hi ditchcrawler - yes it have two wires to the sensor. both green - you can see the photo a few post up above the alternator. 

 

Keeping up - thanks, they may well have been swapped, I have tried just switching them over before but no joy

I'll try holding the other one against the engine and seeing if I get a hot reading tomorrow 
 

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Keeping Up - correct they were switched, the top wire was the alarm (needs recrimping) and the bottom wire turned the temperature dial to full (thanks Tracy D'arth).

But it did not stay readying full hot when the wire was disconnected, as Tracy D'arth suggested above, or was that a typo?...

 

So I'm assuming fault must be with the sensor - thank you all for your insights

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3 minutes ago, Boat_Around_Si said:

Keeping Up - correct they were switched, the top wire was the alarm (needs recrimping) and the bottom wire turned the temperature dial to full (thanks Tracy D'arth).

But it did not stay readying full hot when the wire was disconnected, as Tracy D'arth suggested above, or was that a typo?...

 

So I'm assuming fault must be with the sensor - thank you all for your insights

No, the gauge will fall when the wire is removed from ground, I don't know how you misinterpreted that.  So its a cheap fix, a crimp and swap wires, good.

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3 minutes ago, Boat_Around_Si said:

Keeping Up - correct they were switched, the top wire was the alarm (needs recrimping) and the bottom wire turned the temperature dial to full (thanks Tracy D'arth).

But it did not stay readying full hot when the wire was disconnected, as Tracy D'arth suggested above, or was that a typo?...

 

So I'm assuming fault must be with the sensor - thank you all for your insights

You should be able to measure the resistance on the metering between the  contact and to earth with an ohm meter.

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