aq151 help :)

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markle

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Nov 7, 2010
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Hi All, I joined up an age ago but now have a new boat, a very old princess 25 :)

It is an aq151 engine which is in parts which I am gradually putting together and have hit a problem!

I can only turn the cam thru maybe 150 degrees (using the nut on the pulley) or so (the head is on the block and complete), is this normal or does it show a stuck valve, the problem is present both clockwise and anti clockwise.

I had assumed as a non interference motor i could turn thru 360?

I would rather take the head off now and sort if it is bad news than put it all back together and snap the belt or trash the head!

Any advice appreciated :)

Mark
 
Don S

Don S

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Re: aq151 help :)

It is a non interference engine, probably a stuck valve, before you pull the head, pull the valve cover and see if you can figure out which valve is stopping it.
 
M

markle

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Re: aq151 help :)

Arrggg I was really hoping you wouldnt say that! Yes I think it is on number 3 as i can feel the first two lumpy cam rotations, looks like some fun awaits :)

Will probably plus gas everything first to be sure and try to free up but thanks so much for the help I did try quite hard to turn it so if it wasnt bent then it probably is now :)

Mark
 
Don S

Don S

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Re: aq151 help :)

Afraid I would say what? It's NOT an interference engine, you have a valve problem, maybe stuck from rust?
 
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markle

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Re: aq151 help :)

That I had a stuck valve, I was hoping for it to be a safety feature of sorts :)

I do try to remain optimistic although on the plus side it made taking the pulley off easy.

It may be rust, plus gas will be liberally dosed and fingers firmly crossed prior to pulling the head. Thought I was so close to a running motor, sticky vale was the last thing I thought of with the millions of bolts I have identified, previous owner left them in the cabin sink. Pretty much a lucky dip.
 
Don S

Don S

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Re: aq151 help :)

It may be rust, plus gas will be liberally dosed and fingers firmly crossed prior to pulling the head.
Click to expand...

Good Grief man, gas is not a penatrant. Use a good penatrating oil, not gas.. Trying to blow yourself up or something ????
 
Don S

Don S

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Re: aq151 help :)

Ok, that makes sense then, thought you were using gasoline.
 
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markle

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Re: aq151 help :)

Ha ha yes if you knew me well you would know there was a chance of that so good shout, I have blown things up before in good faith! Big thanks for the advice I am keeping everything crossed that it is just sticky rather than stuck but you saved me just popping the belt on and watching something break :). Wish me luck :)
 
Don S

Don S

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Re: aq151 help :)

Before I pulled the head, I would remove the cam and using a brass drift and hammer, thump each valve to see if it breaks loose. Don't beat on it like your trying to drive a nail, just pop it to see if it breaks free.
 
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markle

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Re: aq151 help :)

Good call, will do. Will start with a soak of plus gas and a tweak, if it doesn't shift then pull the cam, I can defo see which one if is by the feel of the lobes turning before it stops.

If not then a 'gentle tap' will be employed. If this doesn't go to plan it will be followed by some great British swearing, a beer and a head pull. If that isn't fun I don't know what is. Thanks Don (very apt btw).
 
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markle

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Re: aq151 help :)

bummer took the cam off and one of the valves is stuck at lowest push, did give a gentle tap but not sure i could get it to go down any further anyway.

Head off it is and have a look from the dark side!

Will update my progress, those head bolts must be FT bolts, as I couldnt shift them. Will take a breaker bar tomorrow but getting paranoid that I will snap them off!
 
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markle

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Re: aq151 help :)

ha ha yes indeed!
head off, valve tapped back up from underneath but it still sticks every time. Cause of problem now diagnosed as a blocked exhaust manifold which has been forcing raw water into 3 and 4 (stuck valve is exhaust on 3). As it will not sit properly despite my best efforts that little valve is coming out (along with the rest) and the head is off for a clean :) New valve will probably do the trick (and a new manifold - i have never seen anything corrode and block like that) but on the plus side I did get the boat cheap due to an unknown water in the pistons issue, not so unknown anymore!
 
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quintonwatts

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Re: aq151 help :)

Glad to see I am not the only person who has suffered from the dreaded water-ingress killer! I'd lost 3 of 6 pistons to water+grit+mud+sand by the time my cracked heads were diagnosed.
 
RogersJetboat454

RogersJetboat454

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Re: aq151 help :)

markle said:
ha ha yes indeed!
head off, valve tapped back up from underneath but it still sticks every time. Cause of problem now diagnosed as a blocked exhaust manifold which has been forcing ray water into 3 and 4 (stuck valve is exhaust on 3). As it will not sit properly despite my best efforts that little valve is coming out (along with the rest) and the head is off for a clean :) New valve will probably do the trick (and a new manifold - i have never seen anything corrode and block like that) but on the plus side I did get the boat cheap due to an unkown water in the pistons issue, not so unknown anymore!
Click to expand...

I assume it's at a machinist for the clean? Are they checking the valve guides, and grinding the valves?
 
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markle

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Re: aq151 help :)

I am in the process of removing the valves, and will be taking it the shop as ports 3 and 4 will need a bit of welding magic to sort the damage (exhaust gasket it sitting on about 3 mm of head!) and they can do a clean while its there. Damage is pretty nasty I am sure it would run but if it blocks again there would probably be nothing to joint the exhaust manifold to left!. Then I will drop the new valve in and lap it to fit properly, try to avoid paying for things I can do (I spend too much as is!).

I will need two new vales, 44mm and 35mm I think.

Any idea where I can get them to suit? Volvo penta have it as a non produced part so no go here and I do like to order online as I enjoy the fun of parcel delivery :)
 
RogersJetboat454

RogersJetboat454

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Re: aq151 help :)

markle said:
I will need two new vales, 44mm and 35mm I think.

Any idea where I can get them to suit? Volvo penta have it as a non produced part so no go here and I do like to order online as I enjoy the fun of parcel delivery :)
Click to expand...

Since this engine is basically an automotive derivative, you may try looking to the automotive aftermarket for the correct sized valves. The machine shop may even be able to assist you with this.

That being said, if the cost of repairing the head were excessive, I personally would be trying to source a new head. Keeping in mind the auto back ground of this engine may come in handy if a reasonably priced head from a marine born engine couldn't be sourced.

I would imagine with Sweden allot closer to you than us, it may be a little bit easier for you. ;)
 
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