Hi everyone,
Well went out to work on the old d8, capped all the coolant lines, top it off with coolant, installed starter ran the wiring for the starter, strapped the 2 new 8d batteries, and bleed the fuel lines, checked to make sure the throttle linkage/rack was not stuck. Turned it over with the injector lines loose just to bleed the air out, (I could not believe how well and fast the engine turned over)
So I tightened up all the fitting and gave it a try, well if she didn't fire right up, I could not believe it, I let it run for a little bit checked all the gauge's oil pressure and so forth, walked around to is if there was any leaks, everything looked good, played with the throttle a couple of times to see if it would rev up and down, then I shut it down. Stopped to have a little lunch happier then hell that it ran.
So after I come down for my high, I decided to flash it up again to see if it would move. It stared right up again I ran it for a couple of minutes than tried to raise the blade, that worked, I put it in gear and let out the clutch lever the engine rpm slowed a bit but nothing, tried it in reverse and the same thing nothing.
Then coolant started to spray up from the top of the closes cylinder head into the cowling, I stopped the engine right way wondering what the heck. I looked around and could not figure out where the coolant was coming from, so I tried running it again and then I could see where it was spraying from, the coolant was spraying from the 3rd pre com chamber, I shut it down again( head hanging low)
So I have two problem that I know of.
1. Why was it not moving, it has a torque convertor clutch system, I was thinking it might not have any fuel in it, (I only had about 6" of fuel in the tank) I'm thinking there was not enough fuel pressure to fill it ( but I really have no idea), has this ever happen to anyone?
2. Coolant leak, I'm thinking the o-ring on the pre-chamber blew, has that ever happen to someone? The question I have is it seemed to spray which I thought was odd, the engine was not up to temp the coolant was luke warm, does the water pump put out enough pressure to spray, or what else could cause this problem.
Any help would be great, thanks

Hi,
have you bled the T/C System as per the Operator's Maintenance Instruction Book for your machine.

Be aware that the fuel tank needs to be topped off each night to stop condensation ruining the T/C--not only that as the fuel is the drive medium it gets hot and so does the fuel in the tank--minimal air space = minimal condensation.

As best I recall back in the day, it was recommended that the fuel level in the tank should never be allowed to get below about one third full when working the machine and to top off the tank after working for the day.

Scans below show bleeding procedure from an OMI for an early D8H 14A, 15A Form No :-31390, Dated 3-55.

Also added is an article on reasons for 3 Stage Fuel Converter overheating, if ever you encounter this.

Hope this helps,
Cheers,
Eddie B.

Thank you very much Eddie, I did not try to bleed the system, I wanted to come home and ask and read up on the issue before I made matters worries,
have you ever experienced a pre-com o-ring problem, I'm hoping it is just the o-ring

thanks again for the information

Hi Team,
after much searching I found a 35A-36A OMI, so here is the procedure from this Book, Form No :- 33078-06, Dated 3-63.


Pre-comb. seals--if the entire cooling system is over pressurizing then it is likely that the chamber has burst-rusted thru etc. or if not, yes--these seals can fail after some short time due to being cut during assembly if not well lubricated with soap/detergent etc.
Currently, when this lock down is over, I have to do for a friend a D311 to reseal all 4 of the top caps of the pre-chambers due to being cut in the past--they have seal material protruding at the large seal diameter at the cyl. head bore chamfer and 2 of the four are leaking during operation. These were likely driven into place by using a block of wood and heavy hammer and not with the Cat suggested tooling. Chambers can be either one or two piece construction.
Cheers,
Eddie B.

Thank you edb,
So I guess the game plan is to bleed the torque convertor as per your instruction, add a bit more fuel in the tank and hopefully that will take care of that problem.
I had full intentions of changing out the pre-chambers to once that have glow plugs once I get the machine home. I was thinking of doing the work now where it sits but it involves a lot of work that I did not consider, remover valve cover, two head bolts per pre chamber. I don't mind doing the work but is it going to fix the problem.
So my question is do you see a problem with running the machine with that type of coolant leak, just long enough to get the TC issues taken care of and to load it on a truck?

Hi,
as long as you can keep water in the radiator top tank by re-filling regularly--replenish whats sprayed out periodically-- you should be OK. Do not let the level drop too much and refill with cold water as you can easily crack the cylinder heads. I wonder if you have air trapped in the rear head.
I think later water manifolds have a temp. gauge adapter plate bolted to them so loosen the plate to bleed the system--may need a new gasket at worst.
Before the advent of the adapter plate we used to bleed the air out by loosening the Temperature gauge sender on top of the rear of the water manifold--BE Careful as the bulb can be stuck either or both in the nut and/or the adapter so go easy and if it seems stuck there is not much you can do--they are expensive so try it and see--if stuck leave it alone.

If bleeding the T/C does not help then you should check the main clutch for snap over when you pull the clutch lever fully back into engagement--it should have around 50 lbs force to snap over centre--measured at the bottom of the plastic/Bakelite handle with a spring scale/balance.

The clutch not locking over can be either that the clutch is adjusted too tight and you have to hold the lever back to get drive--I recall doing a few of these clutches and the one I did had Velvet Touch linings--sintered bronze-- so rust build up between the plates should not be a problem like with organic linings.
Second is the clutch needs adjustment as it is slipping--could be due to rusted tracks, machine sunk into the dirt due to tractor sitting a while, brakes locked on--steering brake bands stuck to brake drums can happen if left locked on in with the park brake lock.
Also be aware you will need a medium amount of engine RPM to get a Torque Converter drive machine to move if it is slightly at all stuck etc.-- as above.
These things were fairly doughy to operate and felt like they were down on power until people got used to them, when in fact they could really push once the T/C loaded up--they do not snap into action like a Direct Drive unit.

Be sure you are in First gear with the Speed Range lever and have the FWD--REV direction lever engaged--it has a neutral position also.

Scans may help.
Cheers,
Eddie B.

Thank you very much Eddie,
The information that you provided me is worth its weight in gold to me and I can't believe the time you spent to help me out, I appreciate it greatly.
I'm going to wait till next weekend to go and play around with the old girl, the temp this week and weekend is a low of -2 to a high of 8 C, so I think it will have a hard time starting, so I'm just going to wait.
I managed to find the O-rings for the pre-chambers 6f1069 $3.49 5b3718 $1.98 6b7021 $4.98, from the local dealer I was surprised he had them in stock, with the covid-19 restrictions it is a bit different getting parts, I have to call them, and they will leave them at the gate, and I leave them a pocket full of cash.
We are lucky here in Manitoba we have about 284 cases and 35 active and 7 deaths, which is really low for CANADA, and hopefully it just keeps getting better.

Thanks again
Virgil Cote

Hi Virgil,
you are welcome, and I do not blame you for waiting to work on the old girl up there. we are just coming into winter now but today is 20 C, calm and sunny --tomorrow we have rain forecast with 15 C. and winds--bbbrrr.

Working on these machines is like trying to eat an elephant--one bite at a time.

Enjoy and good luck.

As long as people keep ordering parts Cat will keep making and supplying them.
Cheers,
Eddie B.

When you do try to start it again, I suggest you turn it over a few times with the decompression lever on start just in case the chamber has leaked coolant into the cylinder.

Regards

Phil

Hi Guys,
Well I went out to work on the d8,
First I bleed the torque convertor as per Eddies instructions, it took about 1/2 a hour to bleed it, must of been low, I guess it has been sitting for 15 plus years.
Decided to change the pre-chamber that I thought was leaking, removed chamber and the o-ring was cut up pretty good so I thought I got the problem, so I decided to change the other 2 since I had time, but could not get the middle one to move, the splided tool was slipping in the chamber, so I shut the job down (not sure how I'm going to get it out)
I bottoned up everything , and started to fill the rad with water, on the 4th pale, water started to run down the side of the engine, so I looked and water was spraying out of the frost plug next to the pre-chamber so that was my problem to begin with. I sharpened a stick and pounded it in the hole to stop the water and finished filling it. Then I turned it over to bleed the fuel line again ,it was a really bugger to start, took several tries and ether to get it to flash up (temp 9c)
So I had the floor covers off and had it in neutral and released the clutch and the u-joint moved so I put it in gear and she move from it's resting place, tried reverse and that work as it should. So I moved her to the road to get picked up, that was about 1/2"mile, once I got to the road I decided to look over my bush fix and check the oil, well to my surprise the oil looked like mushroom soup, so I quickly shut it down and my head is hanging pretty low thinking nothing is going to go right with this deal.
I call my guy with the low bed to see where he is, well if he isn't have issues with the DOT, so he can't make it.
So the D8 is sitting on the side of the road with a crankcase full of water, if the truck would of been there I would have loaded it and not think anything about it, but now I'm wondering what to do. If I should run it and load it or pull the oil out of it put new stuff in and run it with out water or with water and contaminate another 10 gallons of oil, any thoughts