Shipping dimensions pending
We're verifying exact measurements to ensure accurate shipping costs and delivery times for your location. (Except UAE)
Contact our sales team to get an exact quote
Vendor: European Autospares Trading LLC
Genuine Porsche Engine Sealing O-Ring 99970737140
Dhs. 40.00
Vendor: European Autospares Trading LLC
Genuine Porsche Engine Sealing O-Ring 99970737140
Dhs. 40.00
Description
xGenuine Porsche Engine Sealing O-Ring 99970737140 - 17 x 4 mm Cooling Seal
The Genuine Porsche Engine Sealing O-Ring 99970737140 is the small 17 x 4 mm rubber seal that keeps coolant inside your Porsche's cooling circuit at the expansion vessel, expansion vessel plug, or bleeder valve. It sits in its groove and compresses between the mating surfaces, holding pressure in and air out. When this seal hardens with age and heat, coolant weeps past — dropping the level, triggering warnings, and risking overheating. Fitting the genuine 99970737140 restores the factory seal exactly as Porsche designed it.
This O-ring appears across the water-cooled 911 and mid-engine parts diagrams — the 996 and 997 generations plus the 986 and 987 Boxster and the 987C Cayman. It is the kind of part that is always replaced during cooling service: whenever the expansion vessel or bleeder valve is opened, a new O-ring goes in. The genuine Porsche part gives you the exact 17 x 4 mm profile and the OE compound for coolant and heat resistance, which is why workshops order it by the handful.
How the Cooling O-Ring Works
The cooling system runs pressurised and hot, and every joint in it needs a seal that stays elastic through constant heat cycling. The 99970737140 sits in a machined groove at the vessel or valve joint; when the joint is closed, the ring is compressed to a precise percentage of its cross-section, forming a barrier that coolant cannot pass. The genuine ring's profile and compound are matched to that groove, so the compression stays in the designed range for the full service interval.
Symptoms of a Failed Cooling O-Ring
The first sign is usually coolant weeping — a damp patch or crusty residue around the expansion vessel cap area, plug, or bleeder valve, sometimes with the sweet smell of hot coolant after a drive. The coolant level drops slowly, and on longer runs the low-coolant warning may appear. Left alone, the weep worsens as the hardened ring shrinks further. Any time the vessel or valve is disturbed for service, the old ring should be replaced with the new genuine 99970737140 — old seals almost never reseal properly once removed.
Why the Genuine O-Ring Matters
An O-ring is only as good as its profile and its compound. A generic 17 x 4 ring may look identical, but the wrong elastomer swells, hardens, or takes a permanent set in hot coolant — failing long before the next service. The genuine 99970737140 is the OE-profile ring in the OE compound for this joint, so it seals first time and holds through heat cycles. Given how little it costs against the risk of coolant loss, there is no reason to gamble on an ungraded seal.
Professional Installation Notes
Fitting is a technician's job during cooling service: the old ring is removed, the groove is cleaned of residue, and the new genuine 99970737140 is seated evenly in the groove before the joint is closed. Lightly wet the ring with coolant for seating — never use petroleum grease, and never use sealant, which can block small coolant passages. After the job, the system must be bled correctly and the coolant level checked, since trapped air is a common cause of repeat warnings after cooling work.
Specifications
| Brand | Genuine Porsche |
| Part Number | 99970737140 |
| Type | Sealing O-ring |
| Dimensions | 17 x 4 mm (per Porsche parts catalogues) |
| Material | OE-specification elastomer — exact compound refer to the OE catalogue |
| Application | Expansion vessel / expansion vessel plug / bleeder valve — engine cooling circuit |
| Fitment | Porsche 996 (1998–2005), 997 (2005–2008), 986 Boxster (1997–2004), 987 Boxster (2005–2008), 987C Cayman (2006–2008) — confirm with VIN |
| Condition | Brand new, genuine OEM |
| Packaging | Genuine Porsche factory packaging |
| Quantity | Sold individually — one per service position |
Genuine vs Aftermarket Comparison
| Feature | Genuine 99970737140 | Generic / Aftermarket O-Ring |
|---|---|---|
| Profile accuracy | Exact 17 x 4 mm OE profile for the groove | Sizing can vary, causing under- or over-compression |
| Compound | OE elastomer rated for hot coolant | Wrong compound can swell or harden prematurely |
| Compression set resistance | Stays elastic through heat cycles | Can take a permanent set and start weeping |
| Surface finish | Clean OE moulding, free of flash | Mould flash can create leak paths |
| Service life | Designed to hold the full service interval | Often fails well before the next service |
| Part traceability | Genuine Porsche OE part with factory part number | Usually sold as ungraded bulk stock |
Verification note: Dimensions (17 x 4 mm) and expansion vessel / bleeder valve applications for 99970737140 taken from the Eurospares part record (eurospares.co.uk/parts/99970737140) and Design911 catalogue listing for the 996/986/987 range (design911.co.uk), retrieved 2026-10-13. Generic O-ring failure behaviour described from common workshop experience with cooling seals.
Why Choose European Auto Spares
Exact 17 x 4 mm OE Profile
The genuine 99970737140 seats in the expansion vessel groove with the compression Porsche designed — no guesswork, no weeping after the job.
OE Compound for Hot Coolant
Made in the elastomer Porsche specified for the cooling circuit, so it stays elastic through heat cycles instead of hardening and shrinking.
Always Replace, Never Reuse
We supply the genuine ring fresh in factory packaging, ready for the golden rule of cooling service: new seal every time the joint is opened.
Fitment Verified by VIN
Cooling hardware varies across 996, 997, 986, and 987 variants. Send us your VIN and we confirm the exact position for your car before dispatch.
Worldwide Delivery from Dubai
Order from European Auto Spares for genuine Porsche cooling hardware with fast UAE delivery and worldwide shipping.
Complete the Job
Cooling service usually pairs with ignition and engine work — consider the Genuine Spark Plug For Porsche 911, Boxster, Cayman, Panamera, Cayenne 99917015190 for the ignition service, or the Genuine Porsche Engine Oil Filter 9A719840500 for the same interval. Browse the full Engine Parts collection for genuine Porsche engine components.
Need Help Confirming This O-Ring for Your Porsche?
O-ring positions vary across 911, Boxster, and Cayman model years, and a 17 x 4 mm ring fits more than one joint. Send us your complete VIN and our parts team will confirm the 99970737140 application for your specific car before the order is processed. Order from European Auto Spares for genuine Porsche seals with worldwide delivery.
Stop Coolant Weeps at the Source
A tired O-ring is one of the cheapest parts in the cooling system and one of the most common leak sources. Fit the Genuine Porsche Engine Sealing O-Ring 99970737140 and keep your coolant where it belongs. Order from European Auto Spares today.
Fitment Details
xPorsche O-Ring 99970737140 Fitment
| Porsche Model | Application |
|---|---|
| Porsche 911 (996), 1998–2005 | Expansion vessel / expansion vessel plug / bleeder valve |
| Porsche 911 (997), 2005–2008 | Expansion vessel / expansion vessel plug / bleeder valve |
| Porsche Boxster (986), 1997–2004 | Expansion vessel / expansion vessel plug / bleeder valve |
| Porsche Boxster (987), 2005–2008 | Expansion vessel / expansion vessel plug / bleeder valve |
| Porsche Cayman (987C), 2006–2008 | Expansion vessel / expansion vessel plug / bleeder valve |
Technician's Advisory: A 17 x 4 mm ring fits more than one joint, so always confirm the exact position with your VIN before ordering. Fit the new genuine 99970737140 into a clean, residue-free groove, seat it evenly, and never use sealant or petroleum grease. After the job, bleed the cooling system correctly and recheck the coolant level. Applications sourced from the Eurospares part record and Design911 catalogue listing for 99970737140 (retrieved 2026-10-13).
FAQs
xFrequently Asked Questions
It is a 17 x 4 mm sealing O-ring for the engine cooling circuit — typically the expansion vessel, expansion vessel plug, or bleeder valve. It compresses between two mating surfaces to keep coolant in and air out. Like every rubber seal in the cooling system, it hardens and shrinks with age and heat, eventually letting coolant weep past.
It appears in the cooling system parts diagrams for the Porsche 996 (1998–2005), 997 (2005–2008), 986 Boxster (1997–2004), 987 Boxster (2005–2008), and 987C Cayman (2006–2008), at the expansion vessel, plug, or bleeder valve. Because cooling hardware can vary by model year, send us your VIN and we will confirm the exact position for your car.
Look for coolant weeping or crusty pink residue around the expansion vessel or bleeder valve, a slow drop in the coolant level, the low-coolant warning, or the smell of hot coolant after driving. The golden rule: whenever the vessel or valve is opened for service, fit a new genuine O-ring — old seals almost never reseal properly once disturbed.
No. A used O-ring has taken a permanent set from years of compression and heat, so it will not seal reliably a second time. Sealant is the wrong fix — it can block small coolant passages and makes future service messy. The genuine 99970737140 is an inexpensive part, and fitting a new one is the only correct repair.
This is a brand-new genuine Porsche part in factory packaging, covered against manufacturing defects under the genuine parts warranty, and your statutory consumer rights apply in the UAE. If it arrives damaged or incorrect due to our error, we will replace or refund it. Once fitted, a seal cannot be resold, so we verify your VIN before dispatch.
Found It Cheaper.?
xShipping & Return
xReturns Policy
You may return most new, unopened items within 30 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Shipping
We can ship to virtually any address in the world. Note that there are restrictions on some products, and some products cannot be shipped to international destinations.
When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.
Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.
- Choosing a selection results in a full page refresh.
