How to Replace Onan 10KW Generator Isolation Mounts: Complete RV Repair Guide

Bottom Line Up Front

Based on your 2013 Tiffin Allegro Bus with the Onan 10HDKCA generator, there is likely a part number discrepancy that could explain your premature mount failure. Your parts manual shows four isolators, but the shop used three mounts with a different part number. These may be generic or updated mounts that may not provide the same load distribution and vibration dampening as the original four-mount configuration specified for your generator model. This mismatch could cause the accelerated wear you're experiencing after only 19 months and 34 hours of operation.

The fact that your drain plug is extending below the skid plate again so quickly strongly suggests either incorrect parts were used or the mounting configuration wasn't properly restored to factory specifications. Your instinct to question this before your appointment is spot-on.

Root Causes

Common causes of your rapid mount failure include the use of incorrect isolation mounts. The parts used by the shop may be universal or updated mounts that don't match your generator's specific mounting requirements. Your Onan parts manual specifically calls for four mounts in two different part numbers, which suggests these mounts have different load ratings or positions - typically front/rear or left/right specific applications.

Using three generic mounts instead of four application-specific mounts creates several problems: uneven load distribution across the generator frame, improper vibration isolation characteristics, and potentially incorrect mounting height. The replacement mounts may have a different durometer (hardness) rating or load capacity than your original mounts, causing them to compress more quickly under the 10KW generator's weight and operational vibration.

Another contributing factor could be improper torque specifications during installation. If the shop used generic torque values rather than the specific values for your four-mount system, this could cause premature compression and failure of the isolation material.

Before You Start

Before your appointment, gather all documentation including your parts manual, the previous invoice, and your generator's serial number and spec information. Take photos of the current mount condition and the drain plug position relative to the skid plate. This visual evidence will be crucial when discussing the issue with the technician.

Contact Onan customer service (verify current number with dealer) with your generator model 10HDKCA11506E and ask them to confirm the correct isolation mount part numbers and quantities for your specific unit. Get this information in writing via email if possible. Also ask about any service bulletins or updates related to isolation mounts for your generator model and year.

Research the cost difference between the parts used and the correct parts. If the shop used incorrect but more expensive parts, this could be leverage for getting the repair done correctly at no charge. Typical isolation mounts for this application run $40-80 each, so you're looking at potentially $160-320 in parts costs.

The Repair Process

WARNING: Generator mounting procedures require disconnecting all power sources and following manufacturer safety guidelines. This work should only be performed by qualified technicians using proper lifting equipment due to the generator's substantial weight.

When you meet with the shop, present your documentation professionally and ask them to explain why the different mounts were used instead of the configuration specified in your parts manual. Request that they contact Onan technical support to verify the correct parts and installation procedure for your specific generator model and chassis combination.

The correct repair should involve removing the generator completely, installing the proper four-mount configuration with the correct parts for your model in their specified positions, and torquing them to manufacturer specifications. The generator height should be adjusted so the oil drain plug sits well above the skid plate with proper clearance.

Insist on seeing the old mounts and getting an explanation for why they failed so quickly. Properly installed isolation mounts typically last 5-10 years or several hundred operating hours under normal conditions. Your 19-month, 34-hour failure is completely unacceptable and suggests either wrong parts or improper installation.

Request a warranty on the work that covers both parts and labor for at least 2-3 years. Given the previous failure, ask them to document the installation procedure and take photos showing proper clearances and mount positioning for your records.

Professional Help Needed

While this is definitely a job for professionals due to the generator's weight (approximately 900-1100 pounds) and the need for proper lifting equipment, you should consider getting a second opinion if the current shop cannot adequately explain the part number discrepancy. Contact another Onan authorized service center and ask them about the correct parts for your generator model.

If the original shop refuses to acknowledge the error or won't warranty the work properly, consider involving Onan corporate customer service. They take dealer performance seriously and may provide support for getting the repair done correctly. Document all communications and keep detailed records of the repeated failures.

The repair should take 4-6 hours of labor at $100-150 per hour, plus parts costs. Given that this appears to be a warranty issue from improper parts or installation, push for significant coverage of these costs. A reputable shop should stand behind their work, especially when there's clear evidence of using incorrect specifications.