Yanmar 8 Repair

[bronyar]

I'm recently received a quote to repair a Yanmar 8 engine. The yard owner told me $200-$300 to either repair the loose head bolts or a worn head gasket identified by the surveyor. The same yard is now estimating 10 hours labor and has given me a quote of $850.

Can any offer an opinion of what is reasonable for the respective repairs, re-torque the head bolts or replace the head gasket, respectively?

Thanks.

[Doug Brown]

Hi - to ONLY re-torque the headbolts, you can go buy a torque wrench and correct socket from Sears, Home Depot, Lowes, Harbor Freight Tools, etc for about $100.

Torque wrenches are simple to use - just read instructions.

You should also buy a Yanmar 8 service manual so you can get the proper torque values and the proper bolt tightening sequence. Ydou might be able to find this on-line at some website.

HINT: Torque the head bolts in 2 steps. If it says that the final torque should be 50 foot pounds, set the torque wrench for 40 foot pounds and tighten all the bolts, then re-set the wrench to 50 foot pounds for the final torquing.

If the factory manual givens metric or Newton torque values, you can find conversion values on numerous websites to change them into foot-pounds.

If you have to replace the head gasket, you should probably buy a "head de-carbonizing kit" or "valve job kit" which usually has all the gaskets that you will need to remove and replace the head.

You may need a couple more metric wrenches and sockets to do the job, but you should have those tools onboard anyways. You will also need the torque wrench.

If you have to pull the head, it would be a good idea to at least have the valves lapped or lightly ground. A good machine shop should only charge about $100 to do this.

I don't know how much Yanmar parts are, but the metric wrenches and sockets and a engine manual should cost around $100-150.

So for sockets, wrenches, torque wrench and manual maybe $200-250 for all the tools you will need to remove and replace the head.

Small diesel engines are NOT that hard to work on. Just read the factory manual and go step-by-step. The whole experience is a really important skill set to have for cruising.

Good luck!

[GaryMayo]

By asking the question, I am assuming you are not accustom to doing engine repairs?

If you have no grease under your fingernails, I would vote, let the marina take care of it for you.

A Yanmar 8 is a good engine and pretty easy to work on, I am told. I own that engine in my sailboat. I hire work done on mine, and I have worked as a mechanic years ago. I am so big, I can't get near my engine to work in the engine room. .

[Boracay]

If my quick Google is correct Yanmar 8's are close to 40 years old, which is a very long time for a small engine in a small boat.

Before spending any sort of money it could be wise to take a long hard look at the engine and 1) decide if it's worth repairing and 2) find if spare parts are available.

It's got to be close to a repower. My suggestion is to get the manual, get the tools and practice on this engine.

When you realise it's never going to work properly ever again buy a new modern engine.

You'll now have the skills to install it yourself and with the experience you now have and a bit of love it will last forever.

[bronyar]

Thanks to all for the advice. I am trying to determine if the price is reasonable since the marina's quote flucuated so drastically.

The boat is 300 miles from me and I have a four month leave from work approaching so I want to spend my time sailing when I get down south and leave the repair work to others.

[Ex-Calif]

Originally Posted by bronyar

Thanks to all for the advice. I am trying to determine if the price is reasonable since the marina's quote flucuated so drastically.

The boat is 300 miles from me and I have a four month leave from work approaching so I want to spend my time sailing when I get down south and leave the repair work to others.

I am extremely suspicious of the original diagnosis.

Loose head bolts or a gasket replacement?

Head bolts don't just loosen up. If the symptoms are water where it ain't supposed to be (in the oil) or oil where it isn't supposed to be (in the water) you could have all kinds of other problems.

Either way I can see one guy taking about 6 hours to remove and replace the head gasket. I hope the troubleshooting is correct.

[S/V Antares]

I second X-Calif 's opinion. What did the surveyor see that led him to that conclusion?

[bronyar]

The surveyor stated in his report, "a leak was observed at the joint of the head and block. The cause may be loose head bolts, a worn head gasket or warp int he head."

I received an email from the previous owner stating that he replaced the gasket but did not re-torque the head bolts.

[bronyar]

Thanks Ex-Calif.

[Ex-Calif]

Bronyar - Are you aware of what these defects could mean? A leak of what? Oil, fuel, water, ombustion gas?

Not being smarty pants here but a warped head could be a few thousand dollars to fix.

And if PO says he replaced the gasket but did not torque the bolts, I'd want to know why. And if he did not torque the bolts, how is the engine running?

I am sorry but too many questions here...