Question about water leaking from powerhead bolts on 98 Yamaha 90 HP TLRY

[scisgr8]

Let me state the obvious that I am a novice and looking for some advice. I have a Yamaha 90 HP TLRY, 98 model and it hasn't been started in 7 or 8 years. The last guy I took it to to look at said the engine was locked up and ruined. I've been looking to replace it and started playing around with it a little. Bought new plugs, sprayed starter fluid into the carburetor and to my surprise got the engine to turn over and fire up and then stall out because I have no fuel going to it at the moment (sure I need to somehow clean out the fuel tank since it has been sitting for 7 years).

Many of the bolts to the powerhead have rusted and broke. I noticed when running water through the powerhead that water was leaking from the block where many of these bolts have rusted or broken off. I'm sure this is a problem but don't really know.

I'm attaching some photos of the powerhead and as you can see its in pretty bad shape. I was wondering if I should attempt to back out all the broken bolts and order a new cylinder head assembly and new bolts and give that a try; however I don't want to waste money and time if there is no hope.

If I can repair this motor and these issues, then I can save myself a lot of money without having to repower, because everything else seems to work on the motor.

Any advice would be appreciated.......1. What do about gas tank cleanout since it's been sitting so long. 2. Advice on the water leaking from the block where the bolts have been broken.

 

[flyingscott]

My first impression is the mechanics right. Bolts don't just break off from sitting probably someone tried to remove them and they broke off. Looks like it was overheated pretty good at one time. Do a compression test first the bolts that are broke look like they are only for the water jacket. After that pull the head and look at it. If the bolts just broke off from sitting they should be in the motor somewhere. You might get lucky and it only needs a head.

 

[ondarvr]

Don't use starter fluid to run it like that, some starter fluids have oil in them for use in 2 strokes, most don't, and an engine that hasn't run in a long period of time won't have any excess oil in it and you'll just be doing more damage.

 

[fhhuber]

Tank cleann out depends on how bad it is, tank type and tank size.

Small tank that you can pull, the pull the tank and rinse with some gas (pour in a catch container...) If its bad you can drop in a bunch of 1/4 inch steel balls and shake them around to agitate, then use a magnet to recover the balls.

Sometimes its better to just go ahead and buy a new tank since they aren't all that expensive for a 6 gallon one.

All new fuel lines would not be a bad idea.

*********

Its far more likely that the bolts were removed than that they rusted off.
If they rusted off then the engine will have major corrosion issues and probably won't be worth the time. But an engine that badly corroded would almost certainly be frozen solid.

I have seen a couple of cases where an engine was frozen from overheat and broke free then ran fine. Obviously there would be damage and reduced life. Its best to do a full tear down and see what caused it to get stuck and repair that damage.

Sometimes all you need is to hone the bores and put in new rings. Sometimes it needs to be bored, oversize pistons+rings, full bearing set...

And sometimes you find a broken rod which just happened to move in a way that let the engine turn again. (then it can run really rough for a short time)

Until you know why it was stuck you can't evaluate if its worth fixing. The head has to come off and the crankcase has to be opened.

 

[pilotart]

If you had to pay a professional Yamaha Technician/Shop for the hours necessary to restore this engine, you would very likely far exceed its replacement value. On the other hand, if you enjoy and can do most of the work yourself, it could be very worthwhile.

A search on eBay or Craig's List will give you an idea what these engine's are offered for as well as the prices asked for parts removed from other 'basket-cases'. There is value because you cannot get a 260 pound, 90 Hp from any manufacturer today and your Yamaha 90 has the reputation of being one of the best (if not "The Best") of the last.

Don't buy anything until after you have at least taken it apart, Yamaha parts aren't cheap. Removing broken bolts will be a major project, but will only cost you your time and a few tools and supplies to get it done. You could stop at any point and recover value through sale of what you have as a "Parts" motor or "Parts" you have removed. A compression test would be in order before removing cylinder head, but cylinder head cover could be removed before that and give you some experience with removing broken bolts. Take your time with the bolts to avoid ruining expensive parts (like a $220 Cylinder Head) in their removal.

The good news so far is that you have (with your ill-advised use of starting fluid) determined that you have at least some of your electrical system functional as well as that you are able to turn the crankshaft and move the pistons. See what will drain out from your lower unit to give an idea of its condition and state. An engine which had been submerged and then left to 'sit' for years would most likely be completely frozen and have no electrical capability.

Enjoy your 'project' or sell the parts or the whole thing as a "Parts" motor that is not frozen and has some electrical function.
Art