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Tractor Engine Losing Power

Peter jumped on his tractor, hitched up the topper (bush hog) and drove down the track to Ivy Bottom Field.

It was bright and sunny February day and his trusty Massey Ferguson 675 was singing away like it normally does.

Ivy Bottom Field is a bit bumpy, due to mole hills.  Peter went four times round the headlands with the topper and then something went wrong with the 675.

The tractor suddenly lost all its power, wouldn’t rev past 1400 revs and was pouring black smoke out if you tried to open the throttle.  Peter was scratching his head.

He changed the air filter, checked air pipes for blockages and changed the fuel filters.  Often it is a case of doing the basics, but in this case it hadn’t provided any improvement.

 

Vintage Tractor Engineer Receives A Telephone Call

Peter had taken some logical steps with the air and fuel filters, but sometimes it’s another opinion or mind that may see something different.

When Vintage Tractor Engineer arrived and started the engine (it started OK), the first thing he noticed was a distinct rushing noise from the exhaust pipe.

Removal of the exhaust pipe fixed the problem.  The running characteristics of the engine immediately returned to normal.

It turned out the inside of the exhaust pipe had collapsed and was blocking the exhaust gasses outlet (limiting the speed of exit of exhaust gasses and acting a bit like an exhaust brake that may be fitted to a lorry).

A replacement exhaust and the 675 was soom back to work in Ivy Bottom Field.

 

Tractor Exhaust Pipe

 

 

Tractor World Show, 2015

The 2015 Tractor World Show will be held on 14th and 15th March 2015 at Malvern Show Ground, Worcestershire, WR13 6NW.

 

County Super 6 tractor in show condition

 

2015 SHOW FEATURES
First major show of the year
Turner tractors & machinery display
Displays from most other well known makes
Barn finds/hedgerow themed displays from the regional clubs
Classic tractors including cabbed versions
UK 2015 tractor championship & awards
Stationary engines and equipment
Practical maintenance demos
New tractors on display
New for 2015, spring steam weekend, full size & miniature engines in steam

Other Attractions

One of the attractions to many tractor restorers are all the trade stands full of second hand and obsolete parts.  We can all spend hours rummaging through all the parts, there may just be something you need!

There is an auction of tractors and spares on the Saturday and then a road run on the Sunday.

Tractor World is an event not to be missed.

 

 

Fitting Timing Chain, 4 Cylinder Diesel MF35

Many people find the timing process for the Standard 23C Engine difficult to follow and understand.  We wrote a brief article on fitting the timing chain recently.

The process is shown in full on the MF35 Engine Rebuild DVD, however, we also wanted to provide a written description to help people understand the process.  So here goes…

 

The Procedure

Turn the camshaft clockwise until number 8 valve rises to its highest position.  Then turn the camshaft a further half turn clockwise until the valve is in its lowest position.

Next set the valve gap on number 8 valve to 23 thou of an inch.  Then do the same thing for valve number 7, but to 25 thou (again you need to turn the camshaft clockwise until no. 7 rises to its highest point, then turn another half turn clockwise until it is at its lowest point).  This is done solely with the purpose of keeping things tight for the timing process.

To complete the positioning of the camshaft for timing purposes you need to keep rotating the shaft clockwise until number 8 (exhaust) valve has opened and then closed again and then just before number 7 inlet valve starts to open.  As the valve clearances have been set as we have done them, this will now hold the camshaft in exactly the correct position for us to fit the timing chain.

The next paragraph should be done without the timing chain fitted.
Next, pistons 1 and 4 should be set to Top Dead Centre, this is indicated by the keyway in the crankshaft been in the 6 O’Clock position.  If the engine is disconnected from the rest of the tractor then you can check this with the two arrows lining up on the flywheel.

Temporarily fit the camshaft sprocket and then slide on the crankshaft sprocket and check for alignment (using a straight edge), adding or subtracting shims from/to behind the crankshaft sprocket accordingly.  When you have got that correct you can fit/key the sprocket to the crankshaft.

Now remove the studs from the crankshaft sprocket that you were using to temporarily hold it in place (for alignment using the straight edge)

You can now fit the timing chain over the two sprockets.

 

4 cylinder diesel MF35 timing chain

Next you need to fit the camshaft sprocket in its correct position.  When trialing the fitment of this sprocket you need to place some weight with your fingers to the upper/left part of the chain (between the sprockets) so that the lower/right hand part of the chain is taught.

Don’t move the crankshaft or the chain, but move the camshaft sprocket over a link at a time until you get the sprocket aligned so that the small stud (one of them is smaller than the others) is aligned in the correct place.  You can then fit all the studs.

Make sure your chain tensioner mechanism is in good condition before fitting it.

That’s it.  The crankshaft and the camshaft are now timed!

 

Setting Valve Clearances – AD3.152 engine

Checking and setting the valve clearances is a job which often gets overlooked.  Over time, and with wear in the valve seats, the valve tip clearance becomes reduced.  For this reason, it is important to check the valve clearances.

 

Setting valve clearances

For a full explanation of these procedures, you may find our Perkins A3.152 Engine Rebuild DVD useful.

The Question…

I am setting the valve clearances for the first time ever on my MF135. Can I just check the process – I presume you use a spanner to secure the tappet rod at the bottom, then loosing the lock nut above that and then adjust the clearance by turning the bolt at the top? Am I correct in thinking that this whole assembly is free to rotate, presumably to even out wear on the head?

The cold clearance should be 0.30mm for both inlet and exhaust – the book says to get the TDC line in centre of flywheel inspection hole and check numbers 1,2,3 & 5 – then rotate the flywheel 360 degrees and check numbers 4 & 6 (I presume all numbering is from front of engine back?). I have been surprised to find on my initial check that No.1 valve was close to 0.30mm but every other valve was more or less completely “tight”. Is that unusual or am I doing something wrong?

 

The Answer From VTE…

Firstly, yes all numbering is from the front of the engine back.

As for the “tight” valve clearances, this is not unusual to occur as the engine valves wear against their seats. Everytime the valve clatters against its seat it slowly wears until eventually the vavle starts to receed further into the head which is what narrows the vavle tip clearance.  This is commonly known as “valve seat regression”.

This is why the valve clearances should be checked and adjusted at the appropriate service interval. The recommended vavle tip clearance is 0.012 inches (or 0.3048 mm).

You are correct that the cam followers do rotate during operation, this is indeed to prevent them from wearing unevenly.

Another thing to check before you tighten down the rocker shaft is the oil flow setting to the bearings.  This will have been calibrated and the punch mark scribed in the factory.  The groove in the shaft needs to be lined up with the punch mark.  If you look carefully at the photo at the top of the page, you can just see the punch mark that the groove has been lined up with.

 

 

 

MF35 Timing Chain Replacement

This following question has been asked by someone who wishes to replace the timing chain on their Standard 23C engine.

 

4 cylinder diesel MF35 timing chain

The Question…

I am trying to read the lines between the Engine Rebuild DVD and the Workshop Manual on the subject of Timing Chain Replacement.

I am pulling off the front of my ’59 MF35 4 Cyl Diesel (to get the radiator recored)….so my thinking is “Why not replace the timing chain and tensioner while I’m there?”

Do all I have to do is turn the engine to TDC, hold it with a pin in the flywheel, remove the chain and tensioner and replace…ensuring that the small bolt hole in the camshaft gear matches up when putting tension on the left side of the chain?

Second question, “Would I then have to retime the fuel injector pump afterwards?” I have no idea if this is going to be more complicated than its worth…..the timing chain and tensioner may be ok…..but why not do it, eh?

 

The Answer From VTE…

Firstly is the tractor starting and running OK. If it is all OK, then maybe you don’t need to replace the chain and tensioner.

You can remove the cover to inspect the chain without disturbing any of the timing components. Look to see if the chain links fit on the sprocket teeth centrally (as shown in the DVD). You can replace the tensioner without removing the chain (and without disturbing the timing).

The setting of the valve timing (which is controlled by this chain) has to be done with number 1 cylinder on top dead centre on its compression stroke (i.e. both valves closed). The timing hole in the flywheel holds the engine at 16 degrees before TDC which is used for the injection timing – which is timed after the valve timing has been set using the chain.

If you choose to remove and replace the chain then you will need to follow the timing procedure as per the DVD. Once you have set up the timing of the chain you will need to check the timing of the injection pump.

 

Thanks…

Cheers, you’ve given me the exact info I’m looking for….the tractor is unrestored, but running ok…I get the difference in valve timing vs injection timing now…I hadn’t picked that up before.

So if I replace the timing chain, I’ll need to set up the chain timing and then follow up with the injection timing. Got it.

In my case, I think that I’ll just do an inspection. I just remember rebuilding Standard Engines (Triumph TR3′sand 4′s) back in the day and the timing chain and tensioners were always suspect and had to be done every 30K miles….with this tractor, who knows?….no idea of its maintenance history…but there is no rattle.

 
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