I have a 1975 Cat D3, 79U machine, 45V PC engine. Since I bought the machine it has had a pretty good amount of blow by, but good power and ran great. Today the blow by became pretty heavy out of the draft tube and exhaust, and it lost about 2 gallons of coolant out of the overflow. I quickly shut it down. No oil loss at all, or contamination. Basically I'm deciding to rebuild it. At this point should I do an in frame re-fresh, or remove it and do an out of frame? Also I'm wanting to do the 3 ring pistons and am curious as to information for a good source for a "kit" or supplier........or buy a long block. Any insight is helpful it's a nice machine and relatively low hour, I think its worth the investment. Thanks!
It doesn't have sleeves so I don't know if you can do an in-frame. If the cylinders are bad will have to be bored. IPD makes the 3 ring pistons.
If it were mine, I would pull the head and see what the liners look like before I decided which way to go. If they are wavy by measurement then you know what needs to happen.
Pull the motor and if need be bore and have liners pressed in as mine was done (block has no sleeves).
Thank you for the replies, I'm going to pull the head and dig into int a little this week to get a better feel for what it looks like. Do you remember what it cost you to have sleeves pushed in and have it re-built? I can find long blocks for around 5k or so. But I have an issue with trusting a used "good engine". A guy I know has a 3204 DIT engine that is good, in a running parts machine. But i dont feel like the machine was designed for the increased power. Thanks!
I was over charged by the machine shop but to bore and press fit sleeves it would be about 2K for pistons, gaskets and machine work, or a least in 2018. Maybe another 1K for other stuff My thread HeavyEquipmentForums
3204 is bore in parent block without liners. You only need sleeves/liners if the cylinders are over .040" worn. My engine only needed to be bored .010" over (1 size). Complete rebuild could be 7K+ but depends on what all is needed. (not including the injection pump) If your block is good other than needing to be bored rebuild what you have. Then you know it will go back in and everything will bolt up without issues. Non turbo 3204 can last a long time because it isn't too stressed. Turbo versions in 953's, 943's and D4H's didn't last nearly as long because they were trying to push as much HP as possible.
Costex and Clevite should have the pistons
3 ring like the IPD? IPD has up to .040" over.
Thank you for the input and apologies for the late responses. I'm Looking into the parts resources you all have mentioned, I haven't had time to look the machine over.....hopefully this weekend. Side note, are these engines a pain to purge the air out of the cooling system? I changed some cooling hoses and the thermostat, including flushing the system and I think its air locked. Before this all happened I had coolant flow issues, hot lower hose, cold upper hose. And when running it would sporadically boil over. Thanks!
I think there's a plug you can loosen but can't remember. You could try searching the archives on here.
Ok I'll look for it, should be obvious. One thing I'm looking for is the $800 repair manual, but not for $800. Thank you
Just loosen either a plug on the head or the temp sending unit but it could be a thermostat also have head checked for crack. Normally they purge the air out pretty good. I'm pretty sure I have a spare 931 manual
There is a small hard line which can bleed air
The Cat Publication reference for the manu is REG01357. Like this one on eBay for $230 ......... Only question, is it complete.? https://www.ebay.com/itm/Caterpilla...vice-manual-OEM-6N-79U-REG01357-/114090458116
Thank you I'll check it out. I haven't had good luck with manuals from Ebay, the prints haven't all been complete. I bought one for a bobcat 963G and half of it was missing.
I used the second auxiliary temp sensor plug behind the t-stat. After 4 cycles of pulling the plug, getting steam burned, and adding coolant in it I finally got it bleed. I honestly thought I had lost the engine but apparently it was air locked and got hot, about 220* and started to run like crap and died. After I got the air out, checked oil pressure and valves etc. It seems to be running well, with hardly any blowby at all. I put some hard hours on it this weekend and it did great. Still planning on a re build eventually.
Ask the question of the seller “is it complete?” If they assure you it is and you find it isn’t, IMHO you ought to be able to get your money back under eBay’s “not as described” rule.