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Description
This Rubber Firewall Grommet for 5/8" Heater Hoses (commonly designated by manufacturers under part number RG) is a simple yet vital hardware component for automotive builders, hot rodders, and restoration specialists. Its primary task is to cleanly seal the raw, sharp opening drilled or stamped into a vehicle's sheet metal bulkhead, allowing fluid lines to transition from the engine bay into the passenger compartment without structural damage.
Crucial Hose Wear Protection
Chafing Prevention: Engine torque causes your powertrain to rock and vibrate continuously, while the vehicle body stays rigid. This grommet provides a pliable cushion that prevents the sharp edges of your firewall from sawing into the 5/8" rubber heater hose, eliminating a common source of catastrophic coolant leaks.
Environmental & Fume Shield: By creating a tight, snug fit around the outer diameter of the hose, the grommet seals off the interior cabin. This blocks toxic engine bay fumes, unmanaged heat, road dust, and moisture from infiltrating your floorboards and upholstery.
Mechanical Design & Composition
Premium Molded Rubber: Compounded from oil-, ozone-, and heat-resistant synthetic rubber. It is formulated to survive the intense thermal cycling of an engine bay without drying out, dry-rotting, or cracking.
Tapered Sealing Groove: Features a deep molded center channel that locks firmly onto the sheet metal edge of the firewall bulkhead, preventing the grommet from popping out of place when the heater lines are pulled or shifted.
Technical Installation Specs
⚠️ Important Sizing Note: A 5/8" heater hose refers to the inside diameter (I.D.) of the fluid line. The actual outside diameter (O.D.) of standard EPDM heater hose is generally around 0.91" to 0.95". Consequently, this grommet is engineered with an approximate 7/8" to 1" center pass-through hole, requiring an appropriately sized mounting hole drilled into your sheet metal firewall for a tight, snapped-in-place seat.
Feature
Specification / Detail
Compatible Fluid Line
Standard 5/8" I.D. Coolant Heater Hose
Material Composition
High-Density Automotive Grade Rubber
Primary Utility
Bulkhead sealing, vapor blocking, and hose abrasion protection
Selling Increment
Sold individually (Two are universally required to plumb standard heater core inlet and outlet loops)
It fit better than I expected, it has a great range on the ID and the OD.
Payment & Security
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
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Refund Policy
We offer a 30-day return policy, which means you have 30 days from the date you receive your item to request a return.
Eligibility for Returns
To be eligible for a return, your item must be:
In the same condition as received
Unworn or unused
With original tags attached
In its original packaging
You must also provide a receipt or proof of purchase.
How to Start a Return
To initiate a return, please contact us at jonathon@hotrodhardware.com. Once your return request is approved, you will be provided with the return address and, if applicable, an RMA (Return Merchandise Authorization) number.
Important: Items sent back without prior authorization will not be accepted.
If you have any questions regarding your return, feel free to contact us at the email above.
Damages and Issues
Please inspect your order upon delivery. If your item is defective, damaged, or if you received the wrong item, contact us immediately so we can evaluate the issue and resolve it promptly.
Exceptions / Non-Returnable Items
The following items are not eligible for return:
Custom or personalized products (including special orders)
Hazardous materials, flammable liquids, or gases
Sale items
Gift cards
If you are unsure whether your item qualifies, please contact us before initiating a return.
Exchanges
The fastest way to receive a replacement item is to return your original item (once approved) and place a new order separately.
Free Shipping Orders
Orders that qualified for free shipping are subject to deduction of the original outbound shipping cost if the item is returned.
Refunds
Once your return is received and inspected, we will notify you regarding the approval status of your refund.
If approved:
Refunds will be issued to your original payment method
Any applicable restocking fees will be deducted
Original shipping charges (if applicable) will be deducted
Return shipping costs (if arranged by Hot Rod Hardware) will be deducted
Please note:
Payment processing fees (including PayPal, Amazon Pay, or other merchant fees) are non-refundable
It may take additional time for your bank or credit card provider to process and post the refund
