Centek 4 in. Exhaust Thru-Hull with Flapper 1200326 | White
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Centek 4 in. Exhaust Thru-Hull with Flapper 1200326
- Part Number: 1200326 (Centek Marine)
- Brand: Centek Marine
- Product Type: Marine Exhaust Thru-Hull with Flapper
- Color: White
- Exhaust Hose Size: 4 in. / 102 mm ID
- Construction: Compression-molded fiberglass / fiberglass-reinforced resin
- UPC: 808880120487
Centek 1200326 is a white compression-molded fiberglass marine exhaust thru-hull fitting for wet-exhaust systems using 4 in. / 102 mm inside-diameter exhaust hose. It installs through the transom or hull side at the exhaust discharge point, with the hose connecting to the inside shank and the flange and weighted rubber flapper remaining on the exterior. The external rubber flapper reduces backflow of water through the exhaust outlet when the boat is stopped, moving slowly, or backing down.
Dimensions
- Exhaust Hose Size: 4 in. / 102 mm
- Flange Outside Diameter: 6.00 in. / 152 mm
- Overall Length: 7.75 in. / 197 mm
- Thru-Hull / Shank Length: 4.50 in. / 114 mm
- Weighted external rubber flapper
Compatible Applications
Suitable for:
- Marine wet-exhaust systems requiring a 4 in. / 102 mm exhaust hose connection
- Transom or hull-side exhaust discharge installations
- New builds and exhaust-system replacements where a 6.00 in. / 152 mm exterior flange fits the mounting area
Confirm exhaust hose inside diameter, available hull or transom thickness, required flange diameter, and clearance for the external flapper before ordering.
Replacement Flapper
The external rubber flapper is serviceable separately. If the thru-hull body remains structurally sound, the flapper can be replaced without replacing the entire fitting using Centek repair kit 1200340, which includes a rubber flapper, two mounting screws, and a retaining plate.
Related Part Numbers
- Centek: 1200326 (this part — white, with flapper)
- Distributor/Catalogue Reference: 383-1200326
- Black equivalent with flapper: Centek 1200325
- White version without flapper: Centek 1200324
- Replacement 4 in. flapper repair kit: Centek 1200340
When to Replace the Thru-Hull
- Fiberglass body is cracked or structurally compromised
- Hose-connection shank is damaged or deformed
- Mounting flange or holes are deteriorated
- Exhaust or cooling water leaks around the fitting
- Fitting is being replaced as part of a full exhaust-system rebuild
- Flapper mounting area is damaged beyond serviceability
If only the flapper shows wear, the flapper can be replaced separately using Centek 1200340 — a full thru-hull replacement is not required.
Installation Notes
- Confirm the hull opening and mounting area suit the 6.00 in. / 152 mm exterior flange
- Ensure the mating hull or transom surface is clean and flat before fitting
- Apply a marine-grade sealant around the flange for a watertight installation
- Use 4 in. / 102 mm ID marine exhaust hose on the interior connection
- Tighten all mounting hardware evenly — do not overtighten on the fiberglass flange
- Avoid excessive hose-clamp pressure on the fiberglass shank
- Confirm the flapper opens freely and swings clear of the hull after installation
- Inspect for exhaust and cooling-water leaks after startup
Parts Desk Insights
Best use case: Centek 1200326 is the right choice for any wet-exhaust system running 4 in. exhaust hose where a white fiberglass outlet is preferred — common on vessels with white transoms or hulls where a black fitting would stand out. The compression-molded fiberglass body resists the corrosion that affects metallic exhaust fittings over time, and the weighted external flapper is effective at reducing water ingestion when the boat is stopped or backing down.
Common issue: The most frequent ordering error is not confirming the exterior flange diameter before purchasing. At 6.00 in. / 152 mm, the flange is significantly larger than the 4 in. hose connection — the available mounting area on the transom needs to be verified before ordering. Customers also sometimes replace the complete thru-hull when only the rubber flapper has failed; the Centek 1200340 flapper repair kit is the more economical fix when the fiberglass body is still in good condition. Also confirm whether a flapper is needed at all — Centek 1200324 is the white 4 in. version without a flapper, suited for applications where the flapper is not required or is undesirable.
Shop all exhaust components in our Exhaust Systems collection or browse Engine Parts & Maintenance for related components.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.