4718 Engine Problems

[liamjamesobrien]

Hi guy and girls
My Fathers 4718 has been sitting in a shed for the past 6 years so i think its about time to get my hands dirty and fix it up to its original condition.
My major problem at the moment is the cooling system. As we have had a few cold winters the core/frost plugs in the three cylinder heads have popped out, no big problem. Where my problem lies is that there is water getting into the oil. I have removed all three heads and gaskets etc are ok. im just wondering could it be a joint at the bottom of the cyclinder liner or any other potential weak points.
All sugestions would be greatly welcome
Thanks Liam

 

[ixer0]

Hi Liam

There are 2 o rings on each liner. If you remove the sump and put some water in the block you should be able to see where it is dripping from. If no sign, then it could be a cracked head. If it's up top, you should be able to see if the top of one of the pistons looks a different colour.

Mike

 

[bjarne_iversen]

Hi, sorry to say this but you can have a crack innside your blokk, try takin the pushrod cover off to chek bihinde the rods.
Bjarne

 

[zetor3545]

get your sump off the engine. fill teh water jacket with boiling water with a blue coloured die in it. and with the sump being off youll see where it will be coming from. may be around the liners or worst case a crack.

matt

 

[liamjamesobrien]

Thank a million guys but the 10 points has to go to Bjarne for a very correct answer unfortunatly. After removing the engine i pressure tested the block it in a kind of home made fashion and it was like a waterfall. My next issue is patch or replace but id rather replace the block but as im located in ireland im finding it hard to find 4718's as they seem to be all exported of late. I have come across a 4712 at good value but would the engine block be a suitable replacement and if so what other models could be a potential buy in order to widen my search???

 

[bigdoug]

There are a lot of 3 cylinder 45hp Zetors. To get started, look at tractordata.com Here's the url http://www.tractordata.com/farm-tractors/index.html

 

[liamjamesobrien]

Thanks big doug thats just what i needed

 

[forterra9641]

you can use 4712,4718,4911,5711,5011 etc engine blocs al hree cylinder zetorblocks is alike as long as its a UR1 series good luck

 

[liamjamesobrien]

I have issues with this because i known the 4712 block is the same as my 4718 but according to tractor data the 4718 setup has a Bore/Stroke: 3.937x4.331 inches [100 x 110 mm]
Where as something like the 4911 setup has a
Bore/Stroke: 4.01x4.33 inches [102 x 110 mm]
so my understanding of this is that the 4911 cylinder Barrel/Sleeve has an internal diameter 2mm larger than that of the 4718. would it be possible to swap these component as my existing one are in perfect condition ???

 

[zetor3545]

as far as i am aware all the blocks were the same. just the internal diamter of the liner was bigger along with a bigger piston.

you found a block yet?

 

[Renze]

The 9 series engines had a different block and heads, with an extra coolant port inbetween the valve pushrod. They also had bigger intake valves.

 

[liamjamesobrien]

i just missed out on two 4712's for parts but other than that no luck in finding a block as yet

 

[liamjamesobrien]

So the latest is ive got the block welded and found another major leak which was a cracked cylinder head which i have replaced. i have rebuilt the engine with new gaskets and pistons rings but when i torque up the big end/shell bearings on the crank shaft to the newton meter rating i recived from a main zetor dealer the engine refuses to turn. if i undo the nuts the engine will crack? im wondering does anybody have a recommended torque setting for the big side of the conrod or is it possible that i re-fitted the pistons the wrong way

 

[bobnz]

A bit off the beaten track from where you are at but another site for Zetor model info is:
http://www.konedata.net/Traktorit/zetor.htm

Good luck with the tight shaft.

 

[liamjamesobrien]

so ive rebuilt the engine again with new shell bearings piston rings gaskets and the pistons are put in the right way but i now have a knocking comming from the engine which was never there before. i have the cylinder heads torqued to 130 ft lbs and the con-rod ends torqued to 65 ft lbs. any suggestions ??

 

[ixer0]

Hi,

What did you do to stop the big ends locking up ??
Have you kept the correct big end cap on it's respective con-rod ??
You may be able to tell which cylinder is knocking by slackening each injector pipe in turn and listening to see if the knock goes away.

Mike

 

[liamjamesobrien]

Hi mike
Im unsure what your frist point is but each cap was replaced back on its conrod and each piston assembly was put back in its corrosponding cylinder.
One issue i have is with the middle cylinder head that i replaced the injector from the old head doesnt seem to seal as the old one did? its pretty bad on the exhaust stroke there is a clear puff smoke and on the compression stroke there is a slight mist of fuel . no great i know but could this be the cause of knock ???

 

[ixer0]

Hi,

In your earlier post you said you couldn't turn the engine until you loosened the big end. What was the problem and what did you do to cure it ? Is this the cylinder which is causing the knock ?
The injector probably isn't causing the knock unless it is really sick. You could try another or swap from another cylinder. The injector seals on a tapered seat in the sleeve in the head. If it's not perfectly clean it will blow. I use a seat cutter to re furbish bad seats.

Mike

 

[liamjamesobrien]

oh sorry ye i put the piston in backwards and ended up damaging the shell bearings but i replace them fitted them correctly. neither the conrod nor the crank shaft were damaged. one of the heads were replaced but the old injector seems to be very loose in comparison to the snug fit of the injector to the old head

 

[dozer]

Hi, just a thought on why the injector might not seal.Have you replaced copper washer on the end of the injector and if so would it be possible the old washer is still down the injector hole in the head.