Mercury MerCruiser Water Inlet Tube Seal 38970

Mercury MerCruiser Water Inlet Tube Seal — 38970

What This Part Does

The 38970 is a genuine Mercury OEM rubber seal that fits around the water inlet tube connection at the water-pump body or driveshaft housing plate in selected MerCruiser sterndrive assemblies. It maintains the integrity of the cooling-water passage between adjoining components — a small but critical seal whose failure can compromise the sterndrive cooling circuit. Mercury diagrams identify it specifically as the water inlet tube seal, which is distinct from the driveshaft oil seals and other O-rings located nearby in the same assembly.

Compatible Applications

• Selected MerCruiser sterndrive water-pump body assemblies where the Mercury parts diagram specifies 38970
• Selected MerCruiser driveshaft housing plate assemblies where the Mercury parts diagram specifies 38970

38970 appears across more than one MerCruiser sterndrive configuration. Confirm fitment using your exact sterndrive model, drive serial number, gear-housing configuration, and the applicable water-pump or driveshaft-housing diagram. Do not match by diameter or appearance alone — MerCruiser water-pump assemblies contain several seals, O-rings, and gaskets in close proximity that can look similar.

Serial Number & Fitment Notice

Confirm the sterndrive model and serial number against the applicable Mercury water-pump or driveshaft-housing schematic before ordering. Verify that 38970 is shown at the water inlet tube position in your specific diagram. Mercury uses several different seals in the same area, and matching the correct diagram position is especially important when rebuilding the water pump.

Dimensions

Exact dimensions are not published in the Mercury consumer catalog. Confirm fitment via the parts diagram for your specific sterndrive model and serial number, or use the part number on the seal being replaced.

When to Replace

• Water-pump body is removed and the original seal is visibly compressed or distorted
• Rubber has become hardened or brittle
• Sealing lip is torn or nicked
• Cooling-water leakage is visible at the tube connection
• Corrosion or deposits have damaged the sealing surface
• Water-pump service exposes an aged or deformed original seal

This seal should be replaced as a matter of course any time the water-pump body or driveshaft housing is disassembled for service.

Service Interval

Replace at every water-pump service — whenever the water-pump body or driveshaft housing is disassembled. Mercury typically recommends water-pump impeller replacement annually or every 100 hours; the inlet tube seal should be replaced at the same time. Do not reuse a removed seal even if it appears undamaged.

Installation Notes

• Clean the water tube and seal seating surfaces before installing the new seal
• Inspect the water tube for corrosion, deformation, or scoring
• Ensure the seal is fully seated and not twisted
• Inspect the water-pump body insert and adjacent gaskets while the assembly is apart
• Reassemble according to the Mercury service procedure for the specific sterndrive model and serial number

Alternate & Superseded Part Numbers

• 38970 — Mercury / MerCruiser OEM number
• 26-38970 — Mercury catalog prefix format

No superseding number is confirmed. 38970 remains listed as an active Mercury part.

Related Parts

• Mercury MerCruiser Water Pump Repair Kit 89984T5
• Mercury MerCruiser Quicksilver Impeller Kit 8M0104229
• Mercury MerCruiser Water Pump Face Plate 32435
• Mercury MerCruiser Quicksilver Body/Impeller Kit 807151A14

Technical FAQ

Q: Is this the same as the driveshaft oil seals in the water-pump assembly?
A: No. The 38970 is specifically the water inlet tube seal — it seals the cooling-water passage at the tube connection. The driveshaft oil seals are separate components in the same assembly. Match by diagram position and part number, not by location estimate or appearance.

Q: Do I need to replace this seal every time I change the impeller?
A: Yes, as a best practice. Any time the water-pump body is removed, the inlet tube seal should be replaced. It is inexpensive and takes a permanent compression set when installed — reusing it risks cooling-water leakage after reassembly.

Q: Is 38970 used on all MerCruiser sterndrives?
A: No — it is used across multiple sterndrive configurations but not all. Confirm by checking the water-pump or driveshaft-housing diagram for your specific sterndrive model and serial number.

Q: What other seals and gaskets should I replace at the same time?
A: While the pump is apart, replace all gaskets, seals, and O-rings in the assembly — including the face plate gaskets, pump base gaskets, and any other seals shown in the diagram. A complete water pump repair kit such as 89984T5 includes many of these components together.

Parts Desk Insights

The most common issue with 38970 is customers not realizing they need it until the pump is already apart — it is not typically included in impeller-only kits, so it gets overlooked. If a customer is doing a water pump service, recommend they order this seal alongside the impeller and face plate gaskets so everything is on hand before the sterndrive comes apart. The other frequent point of confusion is distinguishing it from the nearby driveshaft oil seals in the same assembly — always confirm by diagram position (#38970 at the water inlet tube connection), not by physical proximity to the old seal being removed.