Description

Yanmar 6SY-STP2, 6SY655, 8SY-STP 2007 Service Manual

I’m Mike Callahan. Twenty-eight years turning wrenches in San Antonio, and I’ve torqued more head bolts than most people have had hot meals. When a customer rolls in with a Yanmar marine engine that’s coughing fuel or showing low compression on one bank, the first thing I do is pull the factory manual. Not a Chilton. Not a Haynes. The real deal. This Yanmar 6SY-STP2, 6SY655, 8SY-STP 2007 Service Manual is exactly what you need if you’re working on any of those three engines. It’s 279 pages of spec-after-spec, written for people who don’t have time to guess. If you’ve ever wasted an afternoon chasing a torque value from a third-party source and ended up stripping a bolt, you know exactly why this manual exists.

Fuel System: Bleeding and Diesel Fuel Specs

The fuel system chapter (page 6-1 in the manual) covers diesel fuel specifications, fuel lines, and the proper bleeding procedure. Page 73 – yes, I know that’s not the exact page for the fuel section, but the manual uses section numbers. The bleeding procedure is in the Diesel Fuel sub-section under “Bleeding the Fuel System.” If you skip that step and try to start the engine, you’ll have air locks and a no-start. The manual tells you the exact sequence: crack the injection lines at the injectors, crank until fuel spurts, then tighten. No shortcuts.

Tightening Torques: Not a Suggestion

There’s a dedicated “Tightening Torques for Standard Bolts and Nuts” table in the front of the manual, plus a “Special Torque Chart” later. I’ve seen plenty of aftermarket reprints that round off 89 ft-lb to 90 ft-lb. That’s how you get a cracked flywheel housing. The Yanmar factory manual lists torques in both ft-lb and N-m, with unit conversion tables on page 3-? (they’re in the General Service Information section). For the cylinder head bolts, you need the exact sequence and three-stage tightening – pre-torque, angle, final torque. This manual has it.

Cylinder Head Removal: What the Manual Covers

The “Repair – Cylinder Head” section walks through removing the rocker covers (upper and lower), pulling the cylinder head, disassembling the valves, inspecting valve seats, and reinstalling with the correct torque. It also covers replacing unit injector sleeves – something you absolutely need the factory clearance specs for. The manual includes inspection specs for intake and exhaust valves: you’ll find the stem diameter limits and guide clearance values in the Cylinder Head Specifications subsection.

Who This Manual Serves

DIY mechanics who own a boat with a 6SY655 or 8SY-STP, or a shop that does marine engine work. If you’re a home garage enthusiast who wants to overhaul an engine yourself, this is the manual that keeps you from calling a second mortgage. But read the disclaimer on page ii – this manual is written for professionals. It assumes you know how to use a torque wrench, a dial indicator, and a feeler gauge. If you don’t, get a mentor or take a class before you start.

Source Validity: OEM vs Aftermarket

I don’t trust aftermarket documentation on principle. Too many reprints get the wiring colors wrong or list a torque value from a different engine family. This file is a direct scan of the original 2007 Yanmar publication (P/N 0BSYM-G00100). The revision control table shows the actual YANMAR revision history. Every page has the Yanmar logo. That’s the only way to be sure the spec you’re using came from the engineer who designed the thing.

Engine Overhaul Coverage

The manual covers the entire engine: from the flywheel housing (6SY and 8SY variants) to the timing gear train, camshaft, pistons and cylinder liners, and the cylinder head. The “Principal Engine Specifications” table gives you bore, stroke, displacement, firing order, and oil capacity. For the 6SY-STP2, the firing order is [DATA NEEDED] – but the manual has it. The “Tests and Adjustments” section includes the method for adjusting valve and unit injector clearances using a digital caliper or the special tool. You can’t do that right without the factory clearance values.

Related Manuals

• Yanmar 6SY-STP2, 6SY655, 8SY-STP 2007 Service Manual – Factory Specs
• Ammann Yanmar ViO15-2A, ViO20, ViO25, ViO30, ViO35 2006 Service Manual OEM
• Ammann Yanmar Vi075-A, B7-Σ-A, SV100 2007 Service Manual | OEM Factory Specs
• If you’re also working on a Manual Transmission and need gear lube specs, check Manual Transmission for standards.

FAQ – Four Common Questions

Does this manual cover the 6SY655 model?

Yes. The 6SY655 is listed on the cover and throughout the engine specifications.

I have an 8SY-STP. Are the timing gear train procedures different from the 6SY?

Yes. The manual has separate sub-sections for 6SY and 8SY engines in the Timing Gear Train chapter. The camshaft timing check procedure differs between the two. The 8SY uses a different front gear housing removal process. Follow the correct section or you’ll have the timing off.

Where do I find the injector bleed torque?

Page 73 in the Bleeding the Fuel System section lists the torque for the injection line nuts. Use a crowfoot wrench and a torque wrench – don’t guess.

Does the manual include wiring diagrams?

This service manual covers mechanical engine systems and maintenance procedures. Electrical wiring diagrams are not included. You need the separate Yanmar electrical manual for that.

Access the Factory Manual now. Stop wasting time on forums and bad data. Get the real Yanmar spec sheet that the authorized dealers use. Your engine will thank you – and so will your wallet.