7341 OVER HEATING

[aussie_zetor]

I OPERATE A 7341 SUPER AND ARE UNABLE TO STOP IT OVERHEATING. HEAD GASKETS HAVE BEEN REPLACED TWICE, WITH NO OBVIOUS SIGNS OF DAMAGE. IS INJECTION TIMING LIKELY TO HAVE A IMPACT ON ENGINE TEMPERATURE?
TRANSMISSION OIL TEMP ALSO SEEMS TO BE TO HIGH, WHEN RUNNING PTO, MAKING GEAR SHIFTING DIFFICULT. ANY ADVICE APPRECIATED, BEFORE I MAKE THE DECISION TO SELL AND QUIT MY LOSSES

 

[treaney]

Selling it sounds a bit drastic! Try the following:

Change the thermostat. You can test that it opens by putting it into a saucepan of water and heating it up

Water pump? Is this pumping? Is belt properly tensioned?

Do you have any leaks?

Check your radiator cap to see if it is holding pressure

Check that you have circulation through radiator and that none of the cores are blocked. Flush out rad with caustic soda.

Check for internal leaking - this needs a cylinder pressurizing tool. Is the oil get contaminated with water - white stuff in the oil?

Check Your Hoses - older hoses get hard and restrict flow.

 

[Renze]

Overheating engines are mostly a sign of compression loss.
I think you need to test the valves for tightness.
We had a 5245 for 5 years and have allways been annoyed by the poor performance compared to the previous 4712 (with basically the same engine just 12 years older) and its tendency to overheat to 115 C despite its poor performance.

Last autumn i have had the cylinder heads being rebuilt (the valves had doxens of black burn pits in the seats) put in a new thermostat and turned the fuel pump open about 4 or 5 turns... Performance is much better and even when you bring it down to its knees on a heavy cultivator at 40 cm depth, i havent seen temperature exceed 85C yet...

I suppose you burned the valves due to lack of cooling liquid, and now the overheating occurs over and over again because of poor engine efficiency with the bad valves.

Diesel shops can very easily test them by taking both manifolds off and put a small hand operated vacuum tester on the port. only a minute of work per cylinder.

 

[aussie_zetor]

thanks for your responses
The tractor has only done 1300 hours. I have check belts hoses radiator, replace thermostat. When I first purchased the tractor is seemed to loose a lot of water, Motokov who were still operating in Australia then recomended increasing cap pressure to 10lbs, which seemed to work ok. but in the last 18 months doing the same work as previous,it now runs hot. Is it possible to carry out a compression test by removing injectors?

 

[Renze]

You say that it lost a lot of water ?

Does this mean that you have pressure in the cooling system, blowing the water out ?
Maybe you have a cavitation hole in a cylinder linder, causing combustion pressure to blow bubbles in your cooling liquid. However 1300 hrs is mostly not enough time for an engine to cavitate. plus, cavitation is very rare on a Zetor engine.

Yes it is very easy to compression test an engine with the injector replaced by a dummy injector. Most compression test kits come with a box of all sizes of dummy injectors.

There is no absolute measurement for compression pressure because it depends with the temperature, oil, cranking speed etcetera, but all cylinders must measure the same compression and may not differ more than about 10% of each other.

By the way: testing compression with a dummy injector, tests the total engine. Testing with a suction device on the cylinder port, tests the valve only. If the dummy injector compression tests shows a leak it can either be piston rings or valves. If a suction tester shows a leak, you're certain it is the valves. If injector test shows a leak and port vacuuming not, you know its th rings

 

[aussie_zetor]

I HAVE FINALLY BEEN ABLE TO FIND OUT SOME INFORMATION
I WAS REFERED TO PETER LAZNICKA OF AMERICAN JAWA BY ZETOR .CZ.
PETER SAYS " HE HAS VERY RICH EXPERIENCE WITH 7341 OVERHEATING". IN SUMMARY HE SUGGEST THAT I FIT AN UPRATED COOLING KIT 938354 AND FAN 53013010. THIS I HAVE ORDERED ALTHOUGH IT IS EXPENSIVE,THIS PROBLEM HAS RENDERD MY TRACTOR ALMOST IN OPERABLE DURING SUMMER MONTHS. IT HAS ALSO BEEN SUGGESTED THAT I MODIFY BONNET SIDE AND TOP, BY CUTTING HOLES AND FITTING MESH,PER THE LASTEST PROXIMA. THIS I HAVE DONE,I AM ALSO LOWERING BATTERYHOLDER BY 100MM, ALSO MODIFYING AIRCLEANER BY REPOSITIONING INLET TO PROTRUDE THROUGH BONNET AND FITTING PRE CLEANER.ONCE I HAVE FITTED UPRATE RADIATOR ETC I WILL POST MY FINDINGS

 

[Renze]

Ah !! you have one with the fine mazed radiator !!!

..I thought the fine mazed radiator wasnt mounted anymore since the late '80s...
My 5245 was also fitted with the fine mazed radiator and i replaced it with a coarse mazed radiator from a 5718, the first Zetor we had, that was wrecked for parts years later.

I could hardly imagine that this radiator was still used on a Super model, because it was known since long, that this one didnt have enough capacity...

Glad you sorted it out !!