Description

Mitsubishi S6A3-PTA, S6A3-PTK 1991 Parts Catalog – What the Manual Says

You’re pulling a crankcase off an S6A3-PTA and the main bearing cap bolt torque is nowhere in your head. Been there. You flip through three aftermarket PDFs and none of them agree on the washer part number. That’s why this Mitsubishi S6A3-PTA, S6A3-PTK 1991 Parts Catalog sits on my bench. It’s the real deal – printed August 1991 by Mitsubishi Heavy Industries, not some photocopy with blurred out part numbers. 188 pages of factory part listings, group numbers, and application serial numbers. If you’re rebuilding an S6A3-PTK or just need a gasket set, this catalog tells you exactly which part goes where and from which engine number forward it applies.

Group Number Layout – How the Book Is Organized

The catalog splits every engine assembly into group numbers. Crankcase, cylinder head, fuel system, turbocharger – each gets its own section. Page 5 shows the sample layout: group name in Japanese and English, part number, supply code, and a column for model and serial number range. You get the part name – “CRANKCASE ASSY” – followed by dowel pins, washers, main bearing caps, and hanger bolts. Every bolt with a washer is flagged as “B/W” in the notes column. That’s the kind of detail aftermarket catalogs skip. A mistake on a main bearing cap bolt washer thickness means a spun bearing. This book keeps you from guessing.

Does This Catalog Cover Both S6A3-PTA and S6A3-PTK?

Yes, and the difference is spelled out on page 4. S6A3-PTA is a turbocharged engine with an aftercooler. S6A3-PTK is a turbocharged engine with an intercooler. Two distinct air systems, shared block and rotating assembly. The catalog applies to engines from serial number 30339 onward. If you’re working on an earlier engine, cross-check the serial range in the group tables. Part numbers change when Mitsubishi updated the design – the “MODEL & Q’TY” column shows exactly when a new part supersedes the old one. Not a generic “fits all years” situation.

3 Systems You Can Rely On for Correct Part Numbers

• Combination substitute marking (symbol “G” in the code column). When a part is only available as a set of sub-assemblies, the catalog lists the component parts at the end of the book (page E1). No calling the dealer for a list you already have in your hand.
• Assembly bolt reference – bolts with integrated washers are shown as “B/W” in the part name field. Page D1 has a cross-reference table so you can order the bolt and washer separately if needed. That’s a money-saver when you only strip one washer thread.
• Part number index at the back (page C1). Every part number in the catalog appears in numerical order. If you find a box of unmarked bolts, you can look up the number and see exactly where it goes. No staring at a drawer full of fasteners.

Torque Specs and Fastener Data – Where to Find Them

This catalog is a parts catalog, not a service manual. Torque values aren’t printed in the group pages. But the assembly bolt reference page D1 includes bolt and washer dimensions, and the combination substitute page E1 shows which sub-assemblies make up a larger component. For actual tightening specs, you’ll want the matching service manual. Pair this catalog with Mitsubishi S3L2 2009 Parts Catalog – OEM Factory Specs”>a later Mitsubishi small-engine catalog if you need cross-engine familiarity, but for the S6A3 family this is the only source for correct part numbers. The 1991 publication year means it covers the production run before any post-1992 updates.

Who Needs This Catalog?

If you’re opening up an S6A3-PTA or S6A3-PTK for a rebuild, you need this. It’s for the mechanic who doesn’t want to order a crankcase gasket only to find it’s for the intercooler version when you have the aftercooler. It’s for the parts counter guy who needs the exact dowel pin size. The beginner can use it too – the illustration sample on page 5 shows every callout and column header in Japanese and English. You don’t need to read Japanese to follow the part numbers. The same catalog structure is used across all Mitsubishi industrial diesel parts catalogs, so once you learn this layout you can pick up a Mitsubishi 4DQ50 Diesel Engine Parts Catalog”>4DQ50 catalog and feel right at home. Mitsubishi Diesel Engine 4DQ5 Parts Catalogue Aug. ’91″>The 4DQ5 catalog follows the same group numbering system.

Source Validity – Why OEM Beats Aftermarket

I’ve seen aftermarket parts catalogs list the wrong part number for the S6A3-PTA cylinder head gasket because they didn’t understand the aftercooler vs. intercooler gasket differences. This catalog was printed by Mitsubishi Heavy Industries Ltd. in August 1991. The Japanese text on page 3 emphasizes using “MITSUBISHI GENUINE PARTS” only – because imitation parts fail on material and manufacturing method. The same logic applies to the catalog itself: imitation catalogs omit pages, blur drawings, or use generic illustrations. This 188-page document has every page intact, including the blank ones that show pagination wasn’t faked. The Automotive Industry Overview”>automotive industry’s reliance on factory documentation is no surprise to anyone who’s chased a phantom oil leak caused by an ill-fitting O-ring. And if you’re working around the battery system, Automotive Battery”>proper battery maintenance starts with using the correct cable clamp part number – again, found in this catalog.

Frequently Asked Questions

Does this catalog include torque specs for main bearing bolts?

No, this is a parts catalog. Torque specifications come from the service manual. But the catalog lists every bolt and washer separately, including the dowel pins and bearing caps.

What is the difference between “B/W” and regular bolt listings?

“B/W” means the bolt includes a washer in the assembly. The bolt itself has part number xxx, and the washer has its own number. Page D1 cross-references them so you can order each separately if the washer is missing or damaged.

Can I use this catalog for an S6A3 engine built before 1991?

The catalog applies from engine serial number 30339 onward. If your engine is older, you need the earlier catalog. Check the “MODEL & Q’TY” column – it shows the serial number range for each part. Some parts may still cross.

How do I read the group numbers and part code columns?

Page 5 has a detailed sample. Groups are two-digit numbers (07-01 = crankcase). The part number column gives the eight-digit Mitsubishi part number. Supply code “P/G” tells you if the part is currently produced or a combination substitute. The illustration callout numbers (like 1:01) match the drawing above the table.

If you’re rebuilding a Mitsubishi S6A3-PTA or S6A3-PTK diesel engine, this catalog is the difference between ordering the right gasket set and waiting three days for a return. 188 pages, factory diagrams, genuine part numbers. Access the Factory Manual and put it on your tablet or print out the group you need. It’s the same document Mitsubishi dealers used in 1991 – and it still works today.