---
title: "Radiator Cap — $244K/yr Amazon US Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/us/automotive/radiator-cap"
last_updated: "2026-08-07T16:34:24.183Z"
locale: en
meta:
description: "Niche score 59/100 · $244K/yr market. A failed launch gate (market size, growth, or returns) keeps it on the watch list. Data updated Jul 2026."
"og:description": "Niche score 59/100 · $244K/yr market. A failed launch gate (market size, growth, or returns) keeps it on the watch list. Data updated Jul 2026."
"og:title": "Radiator Cap — $244K/yr Amazon US Niche (2026) - Flapen"
---
# **radiator cap**
**Worth a look**
Shows a fragmented shelf (top 5 take 23% of clicks), but a failed launch gate (market size, growth, or returns) keeps it on the watch list.
Market size 46Growth 22Conversion 64Competition 92Returns 53Price range 45Avg price 36Brand share 72Review moat 85Quality gap 76
**Competition**
**Great****23%**
top-5 click share — an open shelf
**Review moat**
**Great****309.48**
avg incumbent reviews — the moat a new listing must climb
**Quality gap**
**Great****4.3★**
avg incumbent rating — lower means beatable quality
**Brand share**
**Good****62%**
top-5 brand share — brands hold most of the demand
**Conversion**
**Good****5.6%**
search→purchase rate — share of searches ending in a sale
**Returns**
**Good****2.9%**
return rate — above 5% kills the launch gate
**Market size**
**Okay****$244K**
$244K/yr · 422K searches
**Price range**
**Okay****$5.07–$23.15**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Avg price**
**Okay****$10.26**
avg listing price — sweet spot $15–$100
**Growth**
**Bad****-6.4%**
90-day search growth — must beat 0% to launch
According to Flapen's Amazon United States niche tracking, radiator cap is a $244K/yr Amazon United States market (422K searches/yr). The top 5 brands hold 62% of demand. Verdict: Worth a look — 59/100.
Data updated Jul 9, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **radiator cap market data**
- **Units sold / yr**
- **25K–30K**
- avg 250–500/product
- **Revenue / yr**
- **$257K–$308K**
- units × avg price
- **Conversion rate**
- **5.6%**
- **Avg BSR**
- **#1,197**
- **Page quality**
- **0%**
- **Prime**
- **100%**
- **Sponsored**
- **58%**
- **Out of stock**
- **1.5%**
- **Avg brand age**
- **48 months**
- **Avg seller age**
- **160 days**
## **Competition & brand share**
Clicks spread well past the top 5 (23% combined) — an open shelf where new products get seen.
**Brands**
**37 **▼falling
**Sellers**
**170**
**Top-5 brand share**
**62%**
Top 20: 91%
**Top-5 click share**
**23%**
Top 20: 55%
**Open market**
**34%**
- Gates23% - MotoRad15% - ACDelco10% - Manymiba9% - RBOKO5% - IHOTDER5%
## **Demand & seasonality**
Weekly Amazon search volume, last 104 weeks — -6.4% search growth over the last 90 days.
9K7K seasonSepDecMarJunAugNovMarMay
No pronounced peak months · busiest ÷ quietest = 1.2×
[**Open Trend **](https://flapen.com/research/us/automotive/radiator-cap/trend)
## **Top radiator cap search terms**
- **radiator cap**342K/yr-6.7%5.6% conv. - **radiator cap replacement**33K/yr-0.6%6.0% conv. - **tapn de radiador**8K/yr+1.6%2.7% conv. - **radiator cap 16 psi**5K/yr+33.3%3.9% conv. - **oem radiator cap**5K/yr+9.9%2.9% conv. - **stant radiator cap**5K/yr+9.8%3.4% conv. - **automotive replacement radiator standard**5K/yr-0.8%3.7% conv. - **tapa de radiador**6K/yr-15.4%1.1% conv. - **radiator cap oem**10K/yr-61.9%4.0% conv. - **radiator caps**3K/yr+7.9%2.4% conv. [**All search terms **](https://flapen.com/research/us/automotive/radiator-cap/search-terms)
## **Top radiator cap products on Amazon**
Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.
0%2%$5K4%$10K6%$15K8%$20K101001K10K Reviews — right = deep review moatMarket share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)
All 24 tracked products in this niche — three views at once, no toggling.
### **Top sellers**
by 90-day click share
[1**Gates 31528 Standard Radiator Cap**Gates**$8.47**4.6★683 rev](https://www.amazon.com/dp/B000C2SCZ6) [2**ACDelco GM Original Equipment RC27 (10409635) Radiator Fill Cap**ACDelco**$10.72**4.7★1,950 rev](https://www.amazon.com/dp/B000C9SP4W) [3**Gates 31336 Radiator Cap**Gates**$12.48**4.4★851 rev](https://www.amazon.com/dp/B000C2WEM8) [4**Car Radiator Cap Coolant Reservoir Cap OEM#16401-31520 1640131520 Standard Radiator Coolant Reservoir Tank Cap Compatible with Lexus Toyota Scion Auto Replacement Parts(for Lexus)**IHOTDER**$5.96**4.6★152 rev](https://www.amazon.com/dp/B0CQR7G14F) [5**Teybouk High Pressure Radiator Cap Cover 1.8 bar Vehicle Radiator Cap Temperature Gauge 1.85 x 2.55 Water Tank Sealing Cover Universal for Suzuki Yamaha Motorcycle ATV Models (Black)**Teybouk**$10.04**3.2★27 rev](https://www.amazon.com/dp/B0FXM4S274)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**Eponcia Radiator Cover 16 PSI Engine Reservoir Cap Stainless Steel Leak-Proof Seal Cover for Radiators Dual-Lug Tank Lid Valve Cap Replacement Universal for Most Cars Fits for Dodge Jeep (Silver)**Eponcia**$5.89**18 rev6mo ago](https://www.amazon.com/dp/B0G6YFGHKK) [**Teybouk High Pressure Radiator Cap Cover 1.8 bar Vehicle Radiator Cap Temperature Gauge 1.85 x 2.55 Water Tank Sealing Cover Universal for Suzuki Yamaha Motorcycle ATV Models (Black)**Teybouk**$10.04**27 rev7mo ago](https://www.amazon.com/dp/B0FXM4S274) [**Radiator Cap for Honda Acura 1992-2005 Civic 1994-2006 Accord 1997-2005 CR-V 1995-2007 Odyssey 2003-2008 Pilot 2001-2006 MDX 1995-2005 TL 1993-1997 Civic del Sol 19045-PAA-A01 19045PAAA01**Manymiba**$9.82**22 rev9mo ago](https://www.amazon.com/dp/B0FSWMFH1D) [**Radiator Cap for Jeep Dodge Chrysler 2007-2017 Patriot 2009-2018 Journey 2007-2017 Compass 2008-2012 Avenger 2007-2012 Caliber 52028810AL 52029195AK 55116901AA**Manymiba**$10.13**31 rev9mo ago](https://www.amazon.com/dp/B0FSXF68JJ) [**RC27 Radiator Cap for Chevrolet Buick GMC Pontiac 1995-2002 Silverado 1991-1996 Corvette 1985-1992 Camaro 1985-1994 S10 Blazer 1992-1996 Yukon 1985-1993 Jimmy 2001 Aztek 10409635**Manymiba**$9.75**10 rev9mo ago](https://www.amazon.com/dp/B0FSWF8K2J)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**MotoRad T208 Racing Radiator cap**MotoRad**$9.58**4.3★**▲ 229%**](https://www.amazon.com/dp/B0BM6PMXCT) [**Radiator Cap for Honda Acura 1992-2005 Civic 1994-2006 Accord 1997-2005 CR-V 1995-2007 Odyssey 2003-2008 Pilot 2001-2006 MDX 1995-2005 TL 1993-1997 Civic del Sol 19045-PAA-A01 19045PAAA01**Manymiba**$9.82**4.8★**▲ 208%**](https://www.amazon.com/dp/B0FSWMFH1D) [**Eponcia Radiator Cover 16 PSI Engine Reservoir Cap Stainless Steel Leak-Proof Seal Cover for Radiators Dual-Lug Tank Lid Valve Cap Replacement Universal for Most Cars Fits for Dodge Jeep (Silver)**Eponcia**$5.89**3.8★**▲ 199%**](https://www.amazon.com/dp/B0G6YFGHKK) [**Radiator Cap for Toyota Scion Lexus 2001-2019 Highlander 2009-2017 Tacoma 2007-2020 Tundra 2007-2017 RX350 2010-2022 RX450h 2007-2016 Sienna 1640131520 1640131480 1640146610**Manymiba**$9.70**4.5★**▲ 164%**](https://www.amazon.com/dp/B0FSX7JZWZ) [**RC27 Radiator Cap for Chevrolet Buick GMC Pontiac 1995-2002 Silverado 1991-1996 Corvette 1985-1992 Camaro 1985-1994 S10 Blazer 1992-1996 Yukon 1985-1993 Jimmy 2001 Aztek 10409635**Manymiba**$9.75**4.8★**▲ 157%**](https://www.amazon.com/dp/B0FSWF8K2J)
**~~View all trending →~~**
## **What buyers say about radiator cap**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Size-Overall**41%
*“Direct fit”*
**Quality-Overall**19%
*“The build quality feels solid”*
**Value For Money**9%
*“Worth it”*
**Advertised Vs Actual Product**8%
*“Just as advertised”*
**Leak-Proof**4%
*“No leaks after installation”*
**Efficiency**4%
*“Works as intended”*
**Pressure**2%
*“Holds pressure well”*
**Coolant**2%
*“Works perfectly, solved my coolant odor problem”*
**Assembly/Installation**1%
*“Easy installation”*
**Strength**1%
*“Well built cap”*
### **What buyers complain about **
**Size-Overall**17%
*“Didn't fit”*
**Compatibility-Overall**17%
*“Does not fit the v6 engine”*
**Leak-Proof**11%
*“will start to leak”*
**Quality-Overall**10%
*“Bad quality”*
**Coolant**7%
*“cause all my coolant to spill out”*
**Advertised Vs Actual Product**6%
*“False info”*
**Heating**3%
*“Truck overheated”*
**Pressure**3%
*“the bar pressure is to high”*
**Functionality-Overall**2%
*“Dose not work”*
**Durability**2%
*“Failed in 3 months”*
### **Top return reasons **
**Size-Overall**61%
**Compatibility-Overall**13%
**Advertised Vs Actual Product**4%
**Coolant**4%
**Pressure**4%
**Defective Material/Parts**3%
**Leak-Proof**2%
**Functionality-Overall**2%
**Value For Money**2%
**Product Condition**1%
## **Common questions**
- **Is radiator cap profitable to sell on Amazon United States?**
- The niche generates $244K/yr across 92 tracked products. 1 of 22 products launched in the last 360 days are still selling. 90-day search growth is -6.4%. Flapen's verdict: Worth a look (59/100).
- **How competitive is the radiator cap niche?**
- 37 brands and 170 sellers compete. The top 5 products take 23% of clicks and top 5 brands hold 62% of demand.
- **What do buyers complain about in radiator cap?**
- Top complaints mined from reviews: Size-Overall, Compatibility-Overall, Leak-Proof. The return rate is 2.9%.
- **When does demand for radiator cap peak?**
- Demand is steady year-round — the busiest month runs 1.2× the quietest.
- **What does it cost to enter the radiator cap niche?**
- Listings span $5.07–$23.15; the average listing price is $10.26 (sweet spot $15–$100). The average incumbent carries 309 reviews — the moat a new listing must climb.
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