Chrysler A-225 overheated - now noisy

[DianneB]

Hi guys! Dianne here aboard my 1966 Lonestar on beautiful Lake of the Woods in N.W. Ontario. I haven't been around much - been busy getting ready for the too-short boating season!

I ran into a bit of a problem .... probably should have changed the pump impeller but I didn't .... When I launched the cooling system didn't prime and the engine somewhat overheated by the time I moved from the ramp to my slip, maybe 10 minutes and the gauge was reading about 240. When I was trying to get the pump to pick up, the exhaust was blowing backward thru thecooling system. I did get the cooling system going but now, shortly after start-up I get this rattling noise like loose tappets or something rattling in the drive train and te noise stays. Everything looks normal - no blue smoke, no blow-by from the crankcase vent so I don't think I buggered it badly but something isn't right.

I will try new sparkplugs but what else could have been effected by overheating? I hope I didn't crack the block!!!

Thanks!

[powerabout]

what is the drive train, shaft/sterndrive?
photos?

[DianneB]

Volvo Penta 270

[whitepointer23]

you should not have exhaust blowing back through the water jackets. either a cracked head or corroded manifold. the tappet noise sounds like compression leaking not tappets. do a compression check before you try anything else. that is very important, without compression readings it is just guess work.

[gonzo]

If the water pump is not pumping water, the exhaust gases will back up into the block. It is not a problem. What is the oil pressure?

[whitepointer23]

Originally Posted by gonzo

If the water pump is not pumping water, the exhaust gases will back up into the block. It is not a problem. What is the oil pressure?

i didn't realise that, i have never run an engine dry for more than a few seconds. so you don't think a compression check should be done. it is the first thing i would do.

[powerabout]

maybe burnt the exhaust bellows (transom plate to drive)and its flapping around?

[PAR]

You could have a number of problems, though it should be pointed out the slant 6 Chrysler engine you have is a solid tappet engine, not hydraulic if memory serves me correctly. If she got good and hot you may have bashed down the tops of the lifters and they need to be adjusted, if not one or two replaced.

The wise thing to do is a full inspection, checking for cracks in the manifold and other likely common problem areas. Check the valve clearance when you pull the valve cover and this will tell you about the lifters.

[DianneB]

Excellent point Par! I will put that on my check list for next trip to the boat.

Fortunately I have a Mercruiser 3.0 + Yamaha outdrive but if I have to do a swap, that will take most of the summer so I am hoping I didn't hurt the slant six.

You are correct - it is solid lifters - and it does sound a little like valve-train noise but it isn't immediate. After starting, it takes 20 to 40 seconds before the noise becomes apparent. It isn't a horrid noise - only someone familiar with that engine would realize it was abnormal.

[GTS225]

Dianne; I am a slant enthusiast, even to the point of racing one, although it's in auto drag racing. I'm not able to diagnose your problem, but you might want to go to http://www.slantsix.org/
There's a good number of folks much more knowledgable than I, and they may be able to give you some more accurate ideas as to where to look.
You'll have to register in order to post, but for someone owning a slant, it's a very good informational resource.

Roger