Caterpillar 12 grader engine is dead - please help?

[Entropy1]

Hello. New member – my first post. I live in Washington State. I have a giant metal lathe, I love metal working, and fixing old machines. I’m happy to be here on these message forums.

I just acquired a Caterpillar 12 grader. I don’t know the year (I’m unable to locate serial number on engine or frame). The backstory is that the grader broke down and was donated to a community college (the diesel department). The college never did anything with it, and they sold it at auction (how I got it).

The college property manager told me the engine was seized. I asked him which engine (pony or the main diesel) – he had no idea. He said the school never got around to fixing it, and that it doesn't run.

Just got it home. Upon initial inspection, all six injectors have been removed from the head (injectors are essentially gone – they didn’t come with the machine). There’s tape over the injector holes, and the engine was covered by the grader’s hood. Nonetheless, I need to borescope the holes to see if there’s any visible corrosion damage in the cylinders, and then attempt to bar it over. At the very least I'll need to track down a set of replacement injectors.

Question: if the original engine is not repairable, are there other options for repower? More specifically – does the CAT D318 share a common bellhousing with any other diesel engines?

I welcome any recommendations on how to proceed with troubleshooting.

 

[OzDozer]

That's a really nice-looking old Cat 12, and it's a shame to hear of it being abused and abandoned by people with no idea. These old Cat 12's are extremely reliable, and their major failing is their braking system, which needs constant attention. The brake wheel cylinders fail on a regular basis, and you need to remove the wheel hubs to access them.

Are the precombustion chambers still in the cylinder head? - or were they removed, too? If so, you will need to source precoms as well as the injectors. The injectors are called "capsule" injectors and are easy to replace.
Both the precoms and the injectors are readily available from many aftermarket suppliers. The D318 was a superb engine and many tens of thousands were built.

Don't even consider an engine swap, it would not be worth the major effort involved, and it would reduce the value of the grader to an even lower level. Cat have never followed SAE engineering standards - they set their own. Typically, a splined shaft with a set diameter, when built to SAE standards, will have X number of splines - but Cat will typically manufacture that shaft, with one number less splines. So Cat conversions are costly.

The serial number tag is located on the side of the main frame, close to the steering box, and just to the rear of it. The engine has the same serial number, and the serial number tag on the engine is located at the upper left rear of the engine block (looking towards the rear of the grader).
If you can't find the S/No tag, but you can see the original small mounting holes, scrape the surface of the frame either side of the holes, the S/No is also stamped into the metal of the main frame.

Once you find the S/No, acquire the Servicemans Reference Books. There is one for the grader, and one for the D318 engine. The grader SRB contains no engine overhaul information - only how to remove the engine from the grader.
eBay is often a good source for manuals. Here's one for the D318.
https://www.ebay.com/itm/224106198274
Cat identify their engines by bore size, as bore size was one of their main standards.

Try to turn the main engine via a wrench on the front crankshaft pulley. If it doesn't want to turn, make up a mix of 50% ATF (Auto Transmission Fluid) and diesel, and pour half a cupful into each cylinder, and let it sit for a week. The ATF and diesel mix will clean up any corrosion and lubricate the piston and cylinder wall, and generally result in the engine freeing up.
The greatest single reason for engines becoming stuck is rainwater entering engines via open exhausts.

 

[Entropy1]

I've looked over the whole engine. I simply cannot find the engine serial number. The front of the grader (above picture) contains the patent information plate, but no serial number plate. I didn't see any unused mounting holes for attaching a label plate. A previous owner weld-attached some angle-iron brackets to the front of the frame. Perhaps these brackets are covering the stamped serial numbers? Does someone have a picture of where the frame and engine serial numbers should be? The frame has been repainted (somewhat thick - could be covering). I can break out the needle-gun to search for stamped serial numbers, however I'd like to narrow my paint removal efforts to where the numbers should be. Note: I did find a serial number on the pony motor's magneto (3A 248216), but I'm not sure that helps.

I also found like some fasters had been pulled from the air piping and coolant piping flanges (and not reinstalled). It looks like someone was in the process of getting ready to pull the engine, and then gave up. Probably not a good sign. . . .

Question - what is the going price for a used D318 (running) - assuming I can source one?

 

[skyking1]

Nice find, best of luck with finding parts. I have nothing else but I do have some knucklebuster experience if you get it going.

 

[OzDozer]

The S/No tag is a tiny tag and it's usually located right next to the much larger lubrication guide plate.

Here's a photo of an electric start D318 in a Cat 12, the S/No tag is arrowed.

I'm not familiar with complete good used engine pricing in the U.S., but I would expect you would have to pay a substantial amount for a good running D318 engine.
Call John Parks at General Gear and Machine in Boise ID, he parts out antique Cats, and he'll be able to advise you of the current price of a good used D318.

https://www.tractorparts.com/cat2.htm

It'll be a much cheaper path to repair the engine you've already got. They're a pretty bulletproof engine.

 

[Entropy1]

Outstanding assistance!
The frame serial number was in fact stamped in (tag missing) just under the welded-on bracket (the one holding up the make-shift headlights).
The engine serial tag was hiding behind the pony motor's magneto - just as pictured above.
Both the engine and frame serial numbers match (numbers are 8T14140).
I suppose it's time to purchase manuals. . . . .

 

[OzDozer]

Great news! There were a total of 21,904 Cat 12 graders produced with the 8T S/No prefix, between 1947 and 1957. They were a very popular machine.

8T14140 was built in 1954 (1954 production ran from 8T13818 to 8T15522) and there will be a range of dismantled Cat graders and new aftermarket parts available for it.

Buy a parts catalog as well, these are very useful for identifying engineering design changes, and how parts fit together.

There are two parts catalogs, the first is 8T1-up, and the second is 8T14782-up. Buy the first one, it will cover your machine, whereas the later one doesn't.

https://www.ebay.com/itm/403993383016

 

[Entropy1]

My plan is to borescope the cylinders first. If clear, see if the engine bars over. If the cylinders are messy (or otherwise seized), I'll probably pull the whole thing and tear it down.

Question - where can I purchase a complete gasket set for the D318 engine? A few websites offer individual gaskets, but not a set. I suppose I can template & cut replacement cork and fiber gaskets, but I'd much rather purchase a complete set (head gasket being the critical part).

I'm going to keep my eye out for a parts machine. I need to score some injectors, and my grader is missing its scarifier attachment.

 

[skyking1]

I would start by oiling it up a little bit before you even considering barring it over. Take a look in there and then get some oil in there to start lubing up the rings.

 

[OzDozer]

Olsons Gaskets do a D318 Cylinder head gasket set, and they can also provide a "lower end" gasket set.

https://www.olsonsgaskets.com/model/d318/

Also, Bulldog do gasket kits ...

https://www.bulldogkits.com/categor...mbers-motor-graders?foo=bar&engine_model=D318

I'm not sure that you'll be able to acquire a full engine gasket kit in one box. It appears that Bulldog make the Cylinder head kit ("Valve grind" kit), and also a Supplementary gasket kit.

John Parks is once again, the best source for a Cat 12 scarifier. There's one currently on eBay, located in TN, and he's asking North of $1500 for it, but it includes the gear drive mechanism, which you already have.

https://www.ebay.com/itm/202652274165

 

[Entropy1]

I paid $1,335 (after sales tax & auction fees) for the grader. Would've had it for 350 bucks but someone else was bidding against me. The real variable is how much will it cost me to get it running?

Question - did the CAT 12 grader ever come with a 4 cylinder? There's supposedly a CAT 12 with a dead 4 cylinder diesel engine not far from me. I might be able to purchase the whole parts machine - mainly for the scarifer attachment. I'm puzzled by the 4 cylinder however. I haven't set eyes on it yet. The guy insists it's a 4-cylinder CAT 12. . . Maybe not a CAT 12, but a smaller version of the same machine?

 

[skyking1]

that's probably a Cat 112
It is a bit smaller and easier to move. That is the knucklebuster I have experience with at the union school.

 

[Entropy1]

Is it a safe assumption that the 112 scarifer will not a 12?

 

[OzDozer]

That's a very cheap Cat 12 for its overall good condition, and it shouldn't cost you a huge amount to get it fully operational again - especially if you have the skills, equipment, tools, and time to do the labour yourself - which you appear to have.

There is no 4 cyl Cat 12, but the Cat 112 and Cat 212 are 4 cyl graders. The 4 cyl graders are deemed "maintenance" graders and the Cat 12 is a "construction" grader. The 12's increased power and weight make it easier to move tougher soil types.

The only way of checking scarifier compatibility is to check the part numbers. It's not entirely unlikely the Cat 12 and the smaller Cat graders use the same scarifier - attachments such as Cat rippers often fit multiple models of machines, with the appropriate installation kit. The Cat scarifier tynes are interchangeable across all models.

 

[kjones95206]

As ususal; OzDozer is giving you some great advice. I echo his recommendation about getting Serviceman's Reference Book for both the grader and the D318 engine, the Parts book, and the Operators and Mainenance book. These books are invaluable in helping you get "acquainted" with the grader. I suggest taking your time assessing the condition of the grader and develop a refurbishment plan after you have evaluated the engines and power train. Undoubtedly, the plan will change after you start but getting your arms around what needs to be done is important. It's difficult to evaluate the grader without the engines running... I think that should be your first step.

 

[Entropy1]

We live in a neighborhood of 5 acre lots. We have a road association (a pseudo-HOA). Our annual budget is 10 grand, and we spend about 6 grand of that per year contracting out road grading services – the rest is spent on purchasing crushed basalt rock. Our neighborhood has about 4.5 miles of rock roads. The guy we hire has a finishing grader, maybe 10,000 pounds, not big enough to cut the crown. All he does is spread out freshly delivered rock and use his blade to clear out the culverts (narrowing our roads a few inches every time). It is quite irritating.

To lower expenses (and in attempt to fix our roads properly) our road association purchased a grader (a Gallion 103). And just like what a bunch of complete morons would do, the Kens and Karins in our neighborhood voted to sell the grader – because “we’ve never needed a grader before” The neighborhood only owned the Gallion for a few months, and just like that we’re back to the same old scenario - where the same 4 or 5 people use their own time & equipment (Kubota tractors) to fill potholes for the benefit of everyone else. Not cool. I tried to explain that if we have a proper crown on our roads, that we’ll have much less potholes to fill. But there’s no arguing with some people. Interesting fact - the folks who voted to sell the Gallion are NEVER seen filling potholes. They simply complain to everyone else – demanding that others fill them on their behalf. The guy who’s been grading our roads is retiring (medical issues). Which is why I purchased the CAT 12. But this time, I own the grader – and not the ignorant road association.

I’m also setting up some nice blast cabinets in the garage – for reconditing parts. I recon the cabinets will come in quite handy while fixing up this grader. One cabinet will use brown aluminum-oxide grit (for cleaning steel and cast-iron parts), and the other cabinet is vapor-blast (water & glass mixture – for cleaning aluminum parts). During the Covid insanity I was sent home for a few weeks. I used the time off to build my air compressor (pictured below - dual compressors, forklift ready, with built in moisture separator). We've got kids - thus wife mandated I incorporate a belt guard, or no compressor.. . . Now if it will just stop raining. . . .

Question - Jensales.com offers electronic copies of the CAT 12 maintenance & parts manuals (PDF format). Is this a good route? I don't mind electronic copies - but 75 bucks per pop seems like a lot - for an electronic copy of an almost obsolete manual? I also need to test the paint on the grader (to see if its leaded paint). I'm assuming the OEM paint is lead-based. A fried is loaning me his borescope this weekend - to inspect the cylinders. The whole injector assemblies are missing (only a threaded hole in the head remains). The exhaust pipe is vertical & open (no muffler, no flapper - just open pipe). The most logical conclusion is that the coffee can was left off and rainwater entered the engine & sized it up. I'll know for sure this weekend. Will keep you guys posted. Maybe I can hone the existing cylinders and install new rings? I see that replacement piston/cylinder kits are about 260 bucks per hole. Not extreme - but not cheap either. . . . .

 

[skyking1]

If you go through with the 112 purchase I might be a buyer for the machine without scarifier.

 

[OzDozer]

That compressor is a very professional looking item, and displays your high level of engineering skills. Satisfactory repair results to an old Cat 12 are obviously well within your skills level.

The general opinion is that Jensales manuals have a poor level of reproduction quality. Purchase the old original Cat manuals/books from the eBay sellers that aren't demanding an arm and a leg for their "priceless antique books". If you can acquire a Military manual, I find they are even more comprehensive and well written. Here is a Military manual on eBay.

https://www.ebay.com/itm/273797190402

 

[Entropy1]

Question - my CAT 12 only has one set of drum brakes (aka the rear axle only). Is this normal? I thought large graders had brakes on both rear axles (all four rear tires).

Assuming for the moment that I track down a CAT 12 parts machine - to rob the scarifier attachment, injectors, and maybe an extra set of drum brakes? More specifically - would I gain anything by installing drum brakes on both rear axles? My plan is to convert the grader over to DOT-5 brake fluid. I've found that DOT-5 is much more forgiving than DOT-3 (DOT-5 doesn't seem to suck up water and size the wheel cylinders). The grader's brake lines have seen better days, and the hoses require immediate replacement (visible cracking all over the rubber). Our neighborhood is generally flat. Only a few short hills - nonetheless, brakes are important. The grader currently has 12-ply 13.00-24 tires all around (all six). The tires are nearing end-of-life - not much tread left. I called my local tire store and they can sell me 12-ply 13.00-24 grader tires for as low as $380 each, up to $650 each. I'm assuming these are tube-type (grader appears to have split-rims). I am going to wait until the machine is running like a top before I entertain the idea of purchasing new tires. The tires currently on it are holding air.

I will purchase paper copies the manuals. Thanks for the heads-up about Jensales. I have used electronic tech-manuals in the past, they work, but I don't like going into the house to look something up while I'm actively working on stuff. I suppose I could get a computer for the garage, but I'm not quite there yet. I purchased a Komatsu manual (PDF) for my little excavator, and a type-o within the hydraulic pilot circuit diagram caused me headaches for weeks.

Regarding the potential 112 parts machine. I was told it worked great until the engine seized. I don't know if it seized during use, or while parked. I haven't discussed price. I only know he's willing to let it go, and he can deliver it. My assumption is that he's not going to want much more than scrap value. . . . . But my assumptions have been wrong in the past. I'll let you know what he says.

 

[skyking1]

cool. I have a soft spot for the 112. I think I can manage it on the tilt trailer.