No Compression in 2 Cylinders
 

Good Morning! ... my name is Keith and Im a newbie here, I just purchased a 1973 Catalina 27 for $1500 in San Pedro CA. The boat seems to be in decent shape except of course for the engine. The boat motor spins freely while attempting to start it and I can hear it firing and almost turning over. A compression test found that the front and rear cylinders have no compression.

I have briefly read up on the atomic 4 and from what I have seen, the valve springs are weak and can get stuck.... so my kneejerk reaction is to spray some Kano Kroil into the cylinder heads and let things sit in hopes that the valves free up. Is this the first course of action one attempts in this instance and is there another thread with an SOP for this? My motor is super tightly squeezed into the Catalina 27 engine compartment so Im not sure I can easily access the valve cover without pulling the motor ... thoughts on this as well?

Thank You in Advance
Keith

I too would suspect seized valves at this point. Continue to read up on various cases of this issue and try some of the suggestions. It would be a good idea to put in any info you know about the engine. Things like when it last ran and if you don't know what things are on it just use your phone to take a few pics. It's a good idea to lower the resolution on the camera when taking pics as well because the site here has a size limit.

See how it goes after soaking it in that oil and report back. I use MMO, but I think I do recall others using the one you mention.

I have a 1974 Catalina (and am in San Pedro as well consequently) and it took some getting used to fitting into that engine compartment. Luckily, I am of smaller stature and frame.

Engine
 

I will be back out there this weekend and take some pics ... the exterior of the engine looks very good ... in fact it has the same bright bronze paint on it that I see on the moyer marine front page.

The boat had a survey done in January of this year so I know the engine ran at that point. The PO said it ran until roughtly 2 months ago. I think he also never closed the cooling seacock to the motor as I found it in the open position... my hopeful assumption is that he only used the boat and never did the required proceedure for start/stop/maintainance ...

you are not the only one there..
https://www.moyermarineforum.com/for...ad.php?t=11680

Sounds like you need to keep putting the penetrating oil to the valves. Here's what I do. I've never had to do it on my own boat but have sorted out a few others. I mix 1/3 transmission fluid and 2/3 acetone ( you only have to mix about half a cup)...it's a very watery mixture but it is just works wicked on stuck valves and rings. Use a flexible tip oil dispenser to shoot it right at the valves. Let it sit a few hours and try it...repeat as necessary. You need to change the oil as soon as you get it running.

MMO on valves
 

Thanks for the good info, Im getting excellent repair and maintainance tips here!

1/3 transmission fluid, 2/3 acetone
8oz MMO with every oil change
TCW-3 in fuel at 100:1

I was out last weekend and added the Kano Kroil to each cylinder, then cycled the motor, added MMO to each cylinder and cycled the motor, then added MMO in each cylinder to let it sit for a week. I will be down there again in the weekend to see if anything unsticks / check compression ... if nothing frees up I will try the transmission-acetone concoction...

Thanks everyone for all the feedback ... I dont feel miserable and alone in this, lol!

Three cylinders now have compression!
 

Good News!

The front cylinder (of 2 that had no compression) now has compression, so thats 3 good cylinders out of four. I switched to the 1/3 transmission fluid 2/3 acetone concoction on this trip and am soaking the cylinders for another week in this stuff. BTW ...heres a funny.... I used a double plastic cup to mix it up and as I was holding the cup and squirting it in the cylinder heads, the acetone melted thru the cup and splashed everywhere, lol... live and learn!!

I did try to start the engine on three cylinders but it wouldn't fire at all due to all the MMO and penetrating oil that was present in the cylinders. What is a good proceedure to clear out the head of the cylinder properly so I can get a proper spark? Is all this MMO gonna gunk up the carburator?

Thanks Again
Keith

you did half of the job!! well done!


my 2 cents, but MVP's opinion are more valuable (by definition):
You should remove the carburetor for sure if not already done, clean it, then spray compressed air (those keyboard cans come handy) into the manifold before installing carburetor back. Regarding whatever is left in the pistons, a few seconds cranking will get rid of all that (if you really have a lot pooling in the pistons, crank without spark plugs but it is going to spray mix everywhere around the engine).

But once you fire it, make sure to change the oil. Not sure if the acetone and all the mix sent is very good for lubrication system..

Sounds good! ... you also have an early Catalina 27... how difficult is carb removal given the tight fit of the engine compartment? I do have an access hatch on the manifold side of the engine... I do have the moyer manual so I will start learning about the carb now... any tips or comments on cleaning a carburator would be super helpful

Thanks
Keith

If there is a lot of acetone\MMO or other liquids in the cylinders take the spark plugs out, lay rag across the spark plug holes, and crank the engine.
A heavy duty shot of starting fluid to the business end of the spark plugs will clean them up and make them usable, at least for awhile.

ex TRUE GRIT

KEEP AT IT. If you can get the engine to start on three cylinders, which you should be able to, betcha the fourth will free up by itself. The carburetor might not need cleaning first - give it a try - what's to loose? You could try draining the carburetor but access is very poor on a Cat 27 so not sure you could do this.
YOU'R ONLY ONE STEP AWAY FROM VICTORY.

ex TRUE GRIT

Please keep in mind that acetone is pretty flammable, and the starter my spark upon activation. So use your nose and sniff around the low points of the bilge, and if you smell any acetone or other fumes, wait until they clear out before triggering the starter.

removal of the carb in a C27 is not that bad; the worst part for me was the throttle cable, the pin refused to come out of the carburetor lever. I had to remove the whole cable assembly and put it on a vise... bad luck. Of course wear long sleeves, as there is a bit of suffering involved.

But I agree with the previous advice, before you try to remove the carb:
- make sure you water valve is closed
- make sure to crank without plugs a couple times, but with large rags on top of the engine and a piece of wood to avoid having the rags fly everywhere (thinking about it, a piece of old carpet would be ideal...)
- make sure everything is well ventilated, no heavy fumes below the floor
- put dry plugs back in, after checking they give you sparks
- and just start it, with start-pilot if needed. very good chance you get the last valve last this. You may have to run some time before it frees itself... check oil pressure and engine temperature during that time (cooling water valve back open...)

and if it works, enjoy the cold beer that tastes "I just avoided an engine removal"

I did pick up a pump for doing the oil after (hopefully) all the cylinders have compression. My thought was to use this to suck any extra fluids out of the cylinder via the spark plug opening, then flushing and sucking out whatever is left in the cylinders to clear everything... was thinking of just using the leftover acetone for this... thoughts? should i use a different liquid to dilute the oil in the cylinders as acetone is somewhat corrosive and quite flammable?

Carb service: Total time about 1/2 an hour.
 

You should remove and clean the carb. Just take your time, disconnect the throttle linkage, choke linkage, fuel supply line and upper part of scavenger tube from the exhaust manifold. Take care not to bend that small copper line (3/8 wrench) as they can be troublesome to reconnect. Keep it lined up.

After that, use a 1/2 wrench to loosen the carb bolts that hold it onto the manifold. Loosen the rear bolt first and start backing it out bit by bit...at some point it will be easily turned with your fingers. Once that is done you start on the front one, closest to you and more accessible. Again back it loose and then you hold or slightly wiggle the carb as you back of the bolt with your fingers...once done lift the carb away from the engine and just take it some where where you can work on it.

There are 4 or 5 (new model) bolts that hold the carb together. Remove them all and gently separate both halves about 1/8 inch. Take care not to damage the gasket, they usually come apart nicely without destroying the gasket. At this point separate both halves and then remove the big round thing in the middle....venturi being careful to work the gasket around and off the venturi.

Now you need a piece of paper towel to lay your clean stuff on....we will call this "laying it off to the side". You will notice the float, bulby looking thing. There's a pin across that holds it in...remove that with your fingers and lay off to the side on some thing clean...lift off the float and do not bend it ...lay off to the side, remove the needle valve and clean the tip with brake clean...ensure it is still pointed but don't be too aggressive on it...light rub between finger and thumb with some brake clean...lay off to the side.

Cleaning jets: You NEED the PERFECT size flat head screwdriver to do that...if you don't have one get one. It must fit the exact slot in the jet without tearing into the side of the hole bore that the jet goes into...we are trying not to mess up the threads. There are 5 different sizes, including the one under the float ...you can make a screwdriver the size you need using a grinder.

NOW put on Safety Glasses for brake clean work. Once all the jets are out you spray everything down with a good brake clean (that's what I use) or carb cleaner. Then ream a small wire through each hole (we are not drilling here, we a pushing through a wire strand that closely fits the size of the hole)....now you spray it again with brake clean and drive it through the passages again. Look through the hole against the light and see that you can see through it ....spray with brake clean again....once you are sure each jet is clean, one by one, spray with brake clean and blow compressed air through them.... lay them off to the side.

Carb Body....clean each part...brake clean the area from fuel intake, jet passages, clean out float bowl ...everything and then blow compressed air through all passages.

Assembly, clean your hands and reassemble taking care not to get any little pieces of dirt on things. I wrote this in case you have never done one before, just take your time and take care on how it comes apart and put it back together the same way. The gasket and venturi assembly are a little bit tricky for the first timer but it's easy, I'm sure you will see how it goes....no major.

Once you have established compression on all 4 cylinders you put your cleaned carb on and she'll fire up....I figure on about the 9th turn.

You are fine. We are talking about a cup of acetone in the oil...a leaking diaphragm could but frank gas into your oil at any time and they don't cause a fire. Once had a guy with a diaphragm leak from the old type pump that thought he had a water leak and it was a gas leak...trouble starting etc, but it would start once he built up pressure. He checked his oil and it was high...so I came to have a look at his engine for a water leak and as soon as I entered the boat I had that "quasy gas" smell...no bubbles on stick, dip stick had a hint of gas on it...gas leak.

If you have remove the carb for cleaning just leave it off until you free up that cyl 4 and have compression on it as well....when you have compression on all 4 and then add a nice clean carb, with good fuel etc it can't help but start.

Try and keep the thing from starting until you have compression on all cylinders anyway....a stuck valve can break and then to have to take things apart....take your time, try and free it, that number 4 is going to be stuck good but it might free up without having to take the head off. Take your time, patience. No guarantee it won't be broken from a previous seizing incident but maybe it will free up with some aggressive treatment...it won't be wished loose.

Keep at it, all the best.

Here's a few carburetor exploded parts diagrams:

ex TRUE GRIT

Here is a a link to my carburetor cleanup and maintenance photos Sept 2020...
 

I traveled down your carburetor road in September with great support and success with the help of this forum.

https://photos.app.goo.gl/6hEzNuvpMshSYB4U6

All the best making progress. You will get there.

Stay well. Tim

and I thought I was taking too many pictures while disassembling :).
showing every single steps will indeed re-assure Keith!

So what is the update on that one? were you able to get compression in the last cylinder? I love stories that ends well..

Please report back.
 

The reason this forum has become so good is because the person who asks for advice tells us if the advice was followed, and if it worked. Then we are all educated. If people are taking the time to give excellent detailed advice, then get no response, they might stop caring. Please tell us you have compression on #4 cylinder, and what you did to get it. Learning works both ways. I suspect the originator of the thread was successful and promptly forgot he ever had a problem. I am also guilty of that.
I should also mention that in 20 years of using MMO in oil and fuel I have never had a stuck valve.
This forum lives on happy endings.