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Cool Telltale with Steamy Exhaust Relief - 1994 Johnson 20HP
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<blockquote data-quote="renn90" data-source="post: 443627" data-attributes="member: 23002"><p>Resolved:</p><p>The issue was due to an under-performing water pump assembly. Water volume was not sufficient.</p><p></p><p>This is what happened:</p><p>* I had used what appeared to be a workable, but not very good, impeller from my parts motor, soon after acquiring the J 20. Wasn't too careful sealing the pump housing as the plan is to do a full service and restore, after sorting things out. (Not such a good idea). The water volumed seemed okay.</p><p>* Checked the motor with a thermal imager, at all RPM ranges on the river.</p><p>* Was getting temps on and around the head averaging in the high around 140s F. One spot was reading 159 F. (According to my manual 160 represents overheating).</p><p>* Ran the motor in a tank, and clamped the telltale hose off; and this caused the motor to run a bit cooler.</p><p>* Replaced all water pump parts and followed installation requirements to a tee.</p><p>* Re-checked the motor with a thermal imager, at all RPM ranges on the river.</p><p>* Now areas on and around the head average around 132 F, with the hottest spot not exceeding 152F.</p><p>* The water coming out the exhaust relief port is only warm at full throttle, but still hot at idle. </p><p>* The tell tale water never goes above luke-warm temperature.</p><p>* Running within specification, and is a very nice motor. Now onto cosmetic restoration.</p></blockquote><p></p>
[QUOTE="renn90, post: 443627, member: 23002"] Resolved: The issue was due to an under-performing water pump assembly. Water volume was not sufficient. This is what happened: * I had used what appeared to be a workable, but not very good, impeller from my parts motor, soon after acquiring the J 20. Wasn't too careful sealing the pump housing as the plan is to do a full service and restore, after sorting things out. (Not such a good idea). The water volumed seemed okay. * Checked the motor with a thermal imager, at all RPM ranges on the river. * Was getting temps on and around the head averaging in the high around 140s F. One spot was reading 159 F. (According to my manual 160 represents overheating). * Ran the motor in a tank, and clamped the telltale hose off; and this caused the motor to run a bit cooler. * Replaced all water pump parts and followed installation requirements to a tee. * Re-checked the motor with a thermal imager, at all RPM ranges on the river. * Now areas on and around the head average around 132 F, with the hottest spot not exceeding 152F. * The water coming out the exhaust relief port is only warm at full throttle, but still hot at idle. * The tell tale water never goes above luke-warm temperature. * Running within specification, and is a very nice motor. Now onto cosmetic restoration. [/QUOTE]
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Cool Telltale with Steamy Exhaust Relief - 1994 Johnson 20HP
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