Help! Cooling issue! Novice

I purchased this boat just a week ago, and this would have been my second outing on it. It's a 1975 Southwind 20 with a ford 351W PCM. First outing went off without an issue. Last night I put her in, she starts right up. I back away from the ramp to allow others to use it and waited for my friend to park the trailer. I was probably waiting for about 6 or 7 min because there was a line back to the dock. I noticed there there was a slight bit of smoke behind me and looked down at the temp gauge that was between 200 and 240. I panicked and immediately shut the engine off. I popped open the engine cover and noticed that both exhaust hoses were smoking, but very lightly. Wisps, like if a hot engine was burning off a drop of oil that had been dripped on it, It wasn't billowing. I left the top open and jumped on the paddle and headed to shore. I pulled the boat onto the trailer as far as I could by hand. I was scared to, but I started it up to get it on the rest of the way. Started off the first bump of the key. Temp was 180. As I gave it more and more throttle to snug up on the trailer the temp immediately started to drop all the way to 160. I need help. I don't know where to start.

I am ignorant in this area. This is my first inboard. I am mechanically competent but l need some instruction and some wisdom here. So feel free to talk to me like you were explaining this to your kid. Won't bother me a bit.

No, I know never to start it out of the water without water hooked up. The only time it was run was while it was in the lake. I am going to go out now and check the impeller and the exhaust hoses. I will get back to you as soon as I dig in.

The Jonny Quest "how to avoid overheating" credo is:

1. Change raw water impeller every 2 years
2. Change thermostat every 3-4 years
3. Change temperature sending unit every 4-5 years
4. NEVER run engine without water.
5. Watch temperature gauge regularly while boating
6. Inspect risers and clean-out with each year's winterizing

Hopefully, your engine didn't get too hot for too long. Heat can screw-up a lot of things. Be vigilant and check your oil for signs of water intrusion. If water is getting into the oil, look under the oil fill cap for residue that looks like chocolate milk. Also, check the oil regularly to see if the oil looks "milky" and kinda like chocolate milk. That can be signs of a cracked head or head gasket issues. Both can occur with overheating.

JQ

Understood. Just picked up impeller to replace. Going to do that now. I was told by the parts guy to check the strainer gasket. Where is that exactly?

John,
Yes, that's the RWP.

Regarding the strainer, you may or may not have up. It's typical location would be between the thru hull water inlet and the trans cooler

Okay, so apparently this is an Escort? 351 pcm. How do I find parts for this? when I went to the local boat shop to get an impeller, they gave me a model specif one for this boat, but it certainly is not the correct impeller. Does anyone know anything about this?

Atomic Dam wrote: Okay, so apparently this is an Escort? 351 pcm. How do I find parts for this? when I went to the local boat shop to get an impeller, they gave me a model specif one for this boat, but it certainly is not the correct impeller.

The proper impeller is for the engine and NOT the boat. I think I'd be shopping elsewhere. .

Escort was purchased by PCM about 1977 or 78 so your engine is a Escort and not a PCM. Some parts interchange and others don't.

Its a Jabsco pump Model 17100-0001. Struggling to find anything

John,
Since it's a Jabsco, here's their chart

Atomic Dam wrote: I found the part online. There was a cross refrence number to a mercruiser engine model that uses that same impeller. It should be here wednesday. I did look and there is no strainer on this engine. But there are two inline canisters that look to have hoses to other engine components. Most notably the transmission. Does anyone know what those are?

If there are two "canisters", then one is the trans cooler and the other is probably an oil cooler. I said probably because a oil cooler isn't a common item on these small engines/boats. A picture will confirm.

Where did you come up with the number to cross reference to the merc?

Through a thorough cleaning, I actually found a faintly printed part number on the one of the blades of the impeller. I typed that in a general google search and several options presented. Most led nowhere, but two led those same parts being sold on amazon, or ebay. One led to a chart that had all the applications that fit specific part along with the manufacturers individual part numbers. I had to take precise measurements to make sure, but i found it. It seems odd to me that on a forum for correct craft that this hasn't come up more often. From everything i have found, this was a relatively routine placement in early 70's correct crafts. I will post a picture with the "canisters" for the hopefully clarification. Because i can find almost no info on these motors. Set up, specifications, nothin.

Sorry that seemed strange, unintentional. I will do that straight away. Im away from the house, i am replying from my phone. Will post more info when i get to my computer.

John,
Here's a link to the eary PCM 302/351 manual that's in the reference section. It will probably give you most information you need for your engine. Take a look and if you need more, ask and we'll see if we can help.

Okay, So here is the site that I got the correct Jabsco part number from. It requires precise measurements of the existing impeller to find the part number for your replacement. After getting the part number and doing a search online, I found that this also has a corresponding Mercruiser part number.

https://pdf.directindustry.com/pdf/jabsco/impeller-replacement/14649-391577.html

The Mercruiser cross reference number is MERCRUISER 34765A1 500106 / JABSCO 920-0001

I found one locally for $80, but decided to order them online. It was on amazon for $20. When it comes in, I will confirm that it was indeed the correct part, and update this thread.

Atomic Dam wrote: 8122pbrainard wrote: John, It will probably give you most information you need for your engine. Take a look and if you need more, ask and we'll see if we can help. The boat actually came with this manual. As much as I have looked through it, it doesn't have anything in there about the escort produced 351. I appreciate you sending that over anyway though.

John,
What else are you looking for? The Escort is basically the same as a early PCM 302/351.

Have you opened up the RWP yet to take a look? Maybe I missed it?