351 overheating |
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cmacbuck69
Senior Member Joined: June-19-2013 Location: Jax, FL Status: Offline Points: 105 |
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I have been having similar issues with my 83 SN. Did the same checks and all is good with the impeller, pump, t-stat, strainer o-ring etc... I pressurized the system with the garden hose and found no water leaks. Then with the bucket water test in the driveway, the RWP was pulling very strong (so the RWP is ruled out for now) yet I was still up around the 200 degree area. Then I checked the circulating pump and the pulley has a bit of wobble to it telling me that the bearings are going bad and it is struggling to take the raw water and push it through the block. Curious if I am on the right path, any thoughts?
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FootFever78
Newbie Joined: September-22-2014 Location: Cicero, IN Status: Offline Points: 24 |
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All good coaching here. I bought the vinyl reinforced hose and plan to use for diagnosis. Really liked the clear hose idea to sight air pockets, etc. If new hose solves the problem I will replace with the right hose. I am desperate for a smooth running, dependable ride. Until that happens, I will be trying most anything. It's function over firm at this point.
Thanks all for the coaching. I hope to have a positive report tomorrow afternoon as that will be my first chance to wrench in a week. First world problems.... |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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John, Your stating the intended purpose of the tubing or hose is correct. You being an engineer I'm sure will also agree that the hg" vac ratings (not low pressure) of each are important before selection for suction sides of any pump. On the suction side of the RWP, I do not suggest anyone to use the braided vinyl tubing "Joe Schmo" found I'm sure at the hardware store. On the pressure side of the RWP has issues as well. Yes, it's braided to resist pressure but it gets real soft as temperatures go up and the reason ratings are given along with temperature. |
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Waternut
Senior Member Joined: July-11-2012 Location: Macon, GA Status: Offline Points: 292 |
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Did you ever figure out this problem?
The clear braided hose is usually pretty stiff at 1" ID. Theoretically, clear braided is really meant to assist positive pressure (inside out). Wire reinforced is meant to resist vacuum (outside in) and resist kicking. Considering the low pressure dealt with in our boats, both are plenty stiff and both resist kinking pretty well. |
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13513 |
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Braided clear vinyl and wire reinforced rubber are not the same.
Bubbles off the hose are because the house pressure isn't enough to supply a revving RWP, not idicative of any air leak. |
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spiralhelix
Senior Member Joined: August-06-2014 Location: IL/WI Status: Offline Points: 496 |
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yes. in my head I had reinforced, guess I typed too quickly. Thanks for the catch Pete.
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Careful - it may collapse. Wire reinforced has been mentioned many times here.as the recommended replacement |
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spiralhelix
Senior Member Joined: August-06-2014 Location: IL/WI Status: Offline Points: 496 |
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UPDATE: I stand corrected. disregard the suggestion below.
fwiw, when we had water pump issues, a buddy just replaced all my intake lines from the through hull to the t-stat housing with 1" I.D. clear braided vinyl tubing. Every time i start the boat, first thing i look at is that water is flowing from the through hull intake, through the strainer, trans cooler, RWP, to the t-stat. piece of mind for $20. |
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3734 |
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I had strainer issues last year. My Oring was not sealing. I filled the Oring slot with silicone, Wiped the clear cover with a thin film of Vaseline and bolted it together and let it cure. It works now and the cover is still removable, but now it seals on silicone rather than the O ring. If I had a spare O ring on hand I would have used it.
On torqueing the hose clamps, the intake hose is large and stiff, nearly impossible to clamp it cold. Warm the engine and the hose if possible and tighten it while warm and you will get a good clamp. If you don't have a good hot sun and a warm engine to work with a hair dryer can heat the hose up pretty quickly. You will be surprised how easy it is to clamp while warm, it gets more flexible. |
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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You can definitely buy a new OEM strainer. Zach can hook you up.
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halfnelly
Senior Member Joined: January-14-2013 Location: Maitland, FL Status: Offline Points: 253 |
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Try running the intake hose and a garden hose into a bucket instead of hooking it up directly to the garden hose. When hooked up directly, the garden hose will supply enough water at idle, but as the pump speeds up it will either pull air or collapse the hose. Using a bucket is much more of a real world simulation to see how much the pump pulls on its own without water being force-fed into the pump. |
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FootFever78
Newbie Joined: September-22-2014 Location: Cicero, IN Status: Offline Points: 24 |
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Update: Checked the strainer and hose from the intake. At idle with a garden hose pushed into the intake end of the hose, there were no bubbles in the strainer. When revving, the bubbles began appearing in the strainer. My next move is to bypass the strainer all-together. The intake hose also looks suspect so I'll be replacing that and all other hoses asap. The intake looks clean now. Will provide another update once able to bypass the strainer and test. This sucker really wants to run. Hopefully I can replace the strainer if needed and/or o-ring(s) and be off the races.
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Pretty unlikely but sounds like it wouldn't hurt to check the actual intake. Maybe someone bottom painted over it or something.
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FootFever78
Newbie Joined: September-22-2014 Location: Cicero, IN Status: Offline Points: 24 |
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Thanks Pbrainard. I did find bits of the old impeller in the housing. I meant to mention that I did check the tstat, which was busted. In fact, half of it (the coil part) wasmissing entirely. Could that be causing a blockage? I replaced that with oem tstat from N3 Boatworks. I did verify the nuts are all back in. I will go over the hoses again with the socket And check the bucket approach again. Will report back asap. Thanks again!
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Jim,
It sounds like you did the needed checking but go over your hoses again. No screwdriver on the hose clamps. You can't get enough torque. Use a nut driver or socket. Overheating at idle indicates sucking air someplace but it could also be a blockage. Check for bits of old impeller at the T stat and at the trans cooler. Was the old impeller busted up? Do use an OEM impeller and not one of the aftermarket ones like Sierra. There are known problems with them. Sucking from the bucket is the best method for troubleshooting since problems aren't masked by direct pressure from the hose. You did find all the missing plugs correct? Welcome to CCfan. We always ask for pictures so when you get the heat issue fixed, post some! |
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FootFever78
Newbie Joined: September-22-2014 Location: Cicero, IN Status: Offline Points: 24 |
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Bought a 92 excel last Fall with a 351 in it and spent the winter reconditioning the boat. This is my first inboard. I ran the engine last week and unfortunately did so without the drain plugs reinstalled (I didn't remember they had been taken out for a quick winterization) Put the plugs in, put in a new strainer with an O=ring, put in a new impeller, and took the boat to the ramp. Engine heated right up to 220. Brought it back to the house and ran it with a garden hose pushed in the hose that goes from the strainer. The boat temp came down to 160. Then replaced that hose on the strainer, and detached the hose from the intake and shoved that in a bucket. It sucked the water in and ran fine at around 160 - 170. Also put that hose down the intake coupling and blew a bunch of junk out of the intake. Thought that was it - took to the ramp and it overheated again. And that's where I am at. I am very coachable here, and while I searched and reviewed threads on "overheating", I wasn't able to locate the same symptoms, I would happy check out any threads someone already knows of. Appreciate the direction.
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