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Discussion Starter #1
I bought a used Ztrac 757 with just under 750 hrs. I looked at a YouTube video that showed accessing the engine to change oil, etc.

The problems I’m having are:
  1. this unit doesn’t have the latches and rotation pivots on the rear cover for access. The two brackets from the rear cover are located on each side of the frame and have slots that would let the cover lift up and back after loosening the two bolts to the frame. However there are two bolts on each side of the cover near the upper forward sides. Hopefully someone can shed some light on this unit so I can change oil, filters, and the like.
  2. I’d also like to find the unit tag so I have the right serial number, etc. so I can find an operator’s manual.
Any help will be greatly appreciated.
 

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Discussion Starter #3 (Edited)
I googled "john deere 757 manual" and found several depending on serial #. Instead of posting the links just google it and click away. Please post some pics!
I did that, but I can’t find the tag with the serial # as you can see in the photo, there’s no tag upper right of the oil filter.

Also the back cover does not swing up like shown. Sorry, I rotated the phone for the last picture.

Added a picture of the identification tag that I found over the right rear wheel. Whoo Hoo
 

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Discussion Starter #4
Stopped by the Deere dealer yesterday to pick up some things and found the 757 is a 2007.

One of the things I went to pick up was the ring clips to hold the deck pulley covers on. Otherwise the covers can blow off while transporting. On Amazon they were about $6.45, GreenParts about $3.27, others pushing $10.00, dealer about $5.80. I bought their spring locking pins instead for $.13 each. I found the diameter about right, but the hole is at a 45* angle so I can’t get them into hole yet so have a little figuring to do yet before I give up on the idea. I’ll see if I can find smaller ones at TSC or somewhere else.

Checked on an Operator’s Manual too, but at $52, I’ll use the on line one for now.
 

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Discussion Starter #5
Stopped by the Deere dealer yesterday to pick up some things and found the 757 is a 2007.

One of the things I went to pick up was the ring clips to hold the deck pulley covers on. Otherwise the covers can blow off while transporting. On Amazon they were about $6.45, GreenParts about $3.27, others pushing $10.00, dealer about $5.80. I bought their spring locking pins instead for $.13 each. I found the diameter about right, but the hole is at a 45* angle so I can’t get them into hole yet so have a little figuring to do yet before I give up on the idea. I’ll see if I can find smaller ones at TSC or somewhere else.

Checked on an Operator’s Manual too, but at $52, I’ll use the on line one for now.
Tried the $.13 Spring Locking Pin again without any luck. Went to Home Depot and got a pair of 1” key rings for $1.48. Took my pliers and bent one side out like the Deere rings and they went right in or out. They weren’t worth the money, but I could spend more than that running after other alternatives so I’m calling it done.

Now on to change deck wheels, oil, oil filter, and grease before putting it away for the winter.
 

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Discussion Starter #6
Figured out I only had to loosen two bolts at the back and the rear cover came right off. The one time last fall I ran it for a little over an hour at near full throttle, the oil light when I returned to idle came on flickering and slowly turned off.

I decided after researching the web, there may be blocked airflow in the head cooling fins. I decided to remove the access plates and found everything was cover with oily dirt on the top of the engine and quite a few areas around the engine compartment. That’s when I decided to take it to the local dealer since they will likely know more than me. I haven’t been a mechanic for a very long time and really don’t want to become one at 71 nor do I want to invest in a lot of tools. Those that I do have allow me to fix most simple things. So, yes the bill will be fairly pricey, but it is what it is. At least the machine will be all cleaned so I can tell if things leak again. In the meantime, I did find a YouTube video showing how to access the heads to get debris out. I was closer than I knew, but I wouldn’t have had the oil leaks solved.

The dealer service dept. sent me a quote for replacing front and rear crank seals, both head gaskets, and both valve cover gaskets, all leaking. Not much material $$$, but about 10 hrs. of labor. No question that would be 30-40 with me doing it. I just don’t want to tackle it this time. At least they guarantee their work for a year. Even with this cost, I’m still just about at the typical $$$ for other machines I found about the same year & hours. This machine runs and starts as good as my X738 EFI, so I’m still satisfied with it. We’ll see how things go with the repair. I’ll keep you posted.
 

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Discussion Starter #7
Well I got the 757 back from the dealer. Found most of the typical issues caused by over heating. Front and rear seals, both head gaskets, Both valve cover gaskets, lower pan gasket, intake gasket, one bent push rod, but no warped heads. Not many $$$ in material, but plenty in labor. I just couldn’t see me fixing all the right things, at least the first time. Repairs came with a 1 yr warranty on the work. I picked up new blades figuring I could change them and got one broke loose, but even with a 4’ pipe on my breaker bar couldn’t get the other two loose. Even bent the pipe trying. Took a second trip back to the dealer who changed the other two at no charge 😲. I know, unheard of right? Looks like it’s ready to run, but no place to go. It’s been snowing all morning. 😞
 

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Discussion Starter #9
Well, I got about 4 hrs of seat time yesterday on 757. Cut was great.

It still acts like it’s getting hot. Anyone every try adding a cooling fan to this engine?
 

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What is the behavior/symptom that makes you think it is getting hot?

Were you running it at Wide Open Throttle? Air (really oil) cooled engines need air flow to stay cool. WOT is where they are designed to run to provide the cooling air needed.

How hot was it outside (air temperature)?
 

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Discussion Starter #11
What is the behavior/symptom that makes you think it is getting hot?

Were you running it at Wide Open Throttle? Air (really oil) cooled engines need air flow to stay cool. WOT is where they are designed to run to provide the cooling air needed.

How hot was it outside (air temperature)?
After mowing 4 acres in about 2 hours, all flat, but some rough, cutting nothing to 6” of grass, I trailered to a place about 8 miles away. I mowed roughly 2 1/2 acres in about 2 hours cutting 3-4” of fairly thick grass in most of it. I drove it up into my trailer and idled down and the oil pressure and charge light came on. The oil light was why I took it to the dealer to get repaired. I didn’t have the charge light before taking it to the dealer, but seems to show up at low Idle sometimes.

Ran at or near WOT both places and this is the first I’ve run it since the engine repair. I’ll have to check the oil level now that it has cooled.

It was low to mid seventies beautiful very sunny day with 5-6 mph wind. Very pleasant.

I don’t know if there is a cooling fan that could be added to help with cooling?????
 

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For the oil light, I would get a pressure gauge and measure it. At idle and WOT, both hot and cold.

It could be the pressure switch is bad. It could be the oil pump is getting weak. It could be a clog somewhere. Some people use heavier weight oil to solve this problem. Did they change the oil, when they did the work? If not, you should do that first.

On my big tractor that has a water cooled diesel engine, if it has been sitting for a long time (weeks) it can take more than 10s for the oil light to go out. But, it's been this way for about a decade, so I am not too worried about it.

You could call the dealer to see what they say, since it is in warranty and that is the issue that caused you to bring it in.

For the battery light, how old is the battery? The battery might be old and tired. Mine does the same thing at idle, but the battery is at least 5 years old, so no too surprising. As long as the battery starts the engine, you can wait till it fails more completely, or replace it now to not have to worry about that. If you have a charger try using that and see if it helps.
 

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Discussion Starter #13
I bought a pressure switch I, so could just change it. They changed oil when they worked on it and put in 5W20 I think and they did check oil pressure to make sure it was okay, The battery light came on at low idle, but went out at mid rpm when I picked it up. It was fine earlier in the day even at low rpm. It just came on after running all day. I wonder if the oil light might have had something to do with driving up the ramp onto the trailer?
 

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5W20 is a generally bad choice for the summer, unless you live in an artic zone. 10w30 is the normal choice, but since you only use this in the summer straight 30W or 10w40 are other choices.
 

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Discussion Starter #15
I checked the owner’s manual and it calls for 5W20.
 

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I have never heard that recommendation before. So, in the interest of learning something new, I checked. I went here, Service Engine
Yes, they do recommend 5w-20, but only up to a maximum air temperature of 0C/32F. 5w20 is a "winter" oil. Even if you asked for it and your dealer put it in without explaining the problem, I would seriously consider the knowledge of the dealer to be suspect.

Given this new information, I would also question all the work they did on the engine. While it might have all been required, it seems excessive to fix an oil leak. Oil leaks are hard to find, since the oil goes everywhere with all the air flow. It is sometimes easier (to not get a callback) to just replace all the seals. Your engine is different than the one in my X534, but mine is known for having an issue with oil leaking from the breather cover. So much so that there is now an improved version available. If this was the original source of the leak and it was neglected long enough, the excess oil could have compromised the cooling enough to cause overheating that could do extensive damage.

Anyway, I don't believe an air-cooled engine will work well with 5w-20 in summer air temps in most places. I would change the oil.
 

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Discussion Starter #17 (Edited)
I have never heard that recommendation before. So, in the interest of learning something new, I checked. I went here, Service Engine
Yes, they do recommend 5w-20, but only up to a maximum air temperature of 0C/32F. 5w20 is a "winter" oil. Even if you asked for it and your dealer put it in without explaining the problem, I would seriously consider the knowledge of the dealer to be suspect.

Given this new information, I would also question all the work they did on the engine. While it might have all been required, it seems excessive to fix an oil leak. Oil leaks are hard to find, since the oil goes everywhere with all the air flow. It is sometimes easier (to not get a callback) to just replace all the seals. Your engine is different than the one in my X534, but mine is known for having an issue with oil leaking from the breather cover. So much so that there is now an improved version available. If this was the original source of the leak and it was neglected long enough, the excess oil could have compromised the cooling enough to cause overheating that could do extensive damage.

Anyway, I don't believe an air-cooled engine will work well with 5w-20 in summer air temps in most places. I would change the oil.
My apologies, You were correct and I went back and checked the invoice. It says they used Turf-Gard Oil 10W30 SN/GFS. When I read things on my phone the print is too small. Darn cataracts.

The dealer has been very helpful and I was expecting the engine to have most gaskets and seals bad due to a known overheating problem on those Kawasaki FH721D engines when they don’t get proper cleaning of the fins on the heads. That’s why they replaced so much, which is what I found on the internet that typically gets changed along with warped heads. I’ll still check oil level (checked - FULL) and for any leaking oil (none found) so I can talk with them, but I’ll probably try it one more time.

Other than that, WOW, does it ever mow - clean, smooth, and fast (easy 2 acres per hour). Hope I can figure out the lights coming on.
 

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That is good then. If it was overheated, it can cause a lot of damage. Leaking oil will decrease the available cooling, so it certainly is possible to have real damage occur.

It sounds like the dealer fixed it well, so you shouldn't have a problem. I have heard of new pressure switches being bad. That could be what's happening or it could be the oil pressure is just under the limit of the switch at slow idle. The gauge will tell you what is happening with better resolution. You can see the pressure at slow idle and also fast idle (WOT) when cold and also when hot. This will give you a very clear picture of how much of an issue it is. The pressure switch turns off at about 15psi (on my engine) but the spec for normal is 35+psi. So, the light on indicates a real problem. If it is only on at slow idle, it probably isn't serious. But, I would still get the gauge and check to make sure. Running an engine with low oil pressure won't kill it in a day, but will increase the wear on it, which could kill it eventually.

Back in the 80's they used to sell pre-start pressurizing systems for cars. Before starting, you press a button which starts an oil pump to pressurize the system. This supposedly eliminated 90% of the wear, since the engine was properly lubricated during starting (which is where 90% of the wear happens). I never bought one and also never had an issue due to poor lubrication of an engine. But, I have heard lots of stories (on the internet, where everything is real and true 😉) of this issue.

The lights are nick named idiot lights, because most people couldn't figure out how to read a pressure gauge and they are cheaper than a gauge. But, my X300 doesn't even have the idiot light, so everyone can be blissfully unaware until it is way too late to do something to prevent damage. Most of the time, none occurs before something else fails, so it is not so bad a system.

But, I would get the gauge to be sure of the health of the engine, since it already had a health issue.
 
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