The Dean RA3146 is an air-cooled, centerline-mounted pump built for hot oil and heat-transfer fluid service ². Most RA3146 pumps that come through our shop do not need a casing or an impeller. They need the rotating element rebuilt: shaft, bearings, mechanical seal, grease seals and gaskets. That is what the 8.5" repair kit, part number 6138148, is for ¹.

PumpResource is powered by Hagler Process in Chattanooga, a Tusk Authorized Service Center for Dean. This post covers what is in the kit, when a rebuild makes sense, what failing seals look like on hot oil, what to check at teardown, and how to confirm fit before you order.

Which pumps the kit fits

Kit 6138148 fits the five RA3146 sizes in the 8.5" casing family: 1x3x8.5, 1.5x3x8.5, 2x3x8.5, 3x4x8.5 and 4x6x8.5 ¹. The 10" casing family (1.5x3x10, 2x3x10, 3x4x10 and 4x6x10 #2) uses kit 6138149 ². The 4x6x10 #1 is an RA3186, not an RA3146, and takes neither kit. The RA IOM shows the RA3146 shaft replacement kit as part number 6138148-49, meaning one kit number for each casing family [³, p. 23, Figure 12].

What's in the kit

Contents per Dean kit drawing #01953H. Item numbers and quantities follow the RA3146 parts list [³, p. 23].

The seal package is built for heat-transfer oil. The stationary (95A) is silicon carbide and Viton. The rotary (95B) is stainless steel, carbon and Viton [³, p. 9]. The seal gland gaskets (325) and front grease seal (76) are Viton, the rear grease seal (76A) and end cover gasket (77B) are Buna-N, and the casing gasket (77) is Grafoil [³, p. 9]. The thrust bearings are an angular-contact pair, 7308 BG on the RA3146 [³, p. 8]. The radial sleeve bearing is carbon [³, p. 8] and is lubricated by the pumped liquid [³, p. 16].

What the kit does not include: the impeller, casing, bearing housing, end cover, fan, casing ring, suction and discharge flange gaskets, bearing grease, and fasteners outside the list above ¹.

Why we usually choose the full kit over individual parts

About 85% of our RA3146 repairs use the full repair kit instead of individual parts, because of the advantages below. The biggest is speed. The kit shaft arrives with the thrust bearings, snap ring, bearing locknut and lockwasher, seal gland with front grease seal and gland O‑rings, mechanical seal and seal collar already assembled on it. The kit comes pre-assembled, with the seal setting done and the bearings fitted. That takes the slowest bench work out of the job. The radial bearing cartridge, rear grease seal, end cover gasket, casing gasket and vent plug come loose, and you install them during reassembly.

The kit's thrust bearings come pre-greased, so the packing the IOM calls for at assembly [³, p. 16] is already done. That is one more advantage of the kit. Leave the seal collar (365) where it is. Moving it changes the seal setting.

If you build the shaft yourself from individual parts, the IOM covers every step [³, pp. 30–32, steps D–M]: thrust bearings pressed back-to-back against the snap ring (75) [³, p. 30, step E2], 2.9 cubic inches (48 cc) of NLGI Grade 2 lithium 12-hydroxystearate grease with rust inhibitors and EP additives forced into the thrust bearings [³, p. 31, step G2], the locknut and lockwasher secured with a bent tab [³, p. 31, step F2], and the seal collar (365) set against the shaft shoulder to load the rotary spring [³, p. 32, step M].

Rebuild or replace the pump?

The kit covers the parts that wear in normal service. The IOM calls for replacing all gaskets, seals, bearings and lubricants at every rebuild, plus any part that is worn, corroded, eroded or otherwise deteriorated [³, p. 30]. The kit covers the internal gaskets, seals and bearings. Have bearing grease on hand for the end cover step [³, p. 32, step R]. Dean sells it as RA3000 Grease #2, one container per RA3146 [³, p. 16]. The condition of everything else decides rebuild versus replace.

Rebuild with the kit when:

• The casing interior shows no significant wear, corrosion or other damage [³, p. 28, step M].
• The impeller and bearing housing are serviceable.
• The service conditions have not changed.

Consider a replacement pump when:

• The casing or bearing housing is damaged. Do not machine or over-bore a seal chamber to save it. That removes metal needed to contain pressure [³, p. 35]. The IOM also prohibits making or modifying pump parts [³, p. 30, reassembly warning].
• The service has changed. The IOM requires a full review of construction, materials, sizing, sealing, pressure and temperature capability before a pump is moved to different conditions [³, p. 11].

If a full pump is the answer, the RA3146 is dimensionally interchangeable with the water-cooled Dean R4140 footprint and mounts on standard ANSI B73.1 baseplates ².

Signs of seal failure on hot-oil service

The RA seal sits behind a barrier cavity. That cavity, between the seal stationary (95A) and the front grease seal (76), lets a barrier fluid keep oxygen off the seal faces when the heat-transfer oil oxidizes [³, p. 16]. Most oils begin to oxidize at 250°F (120°C), some as low as 150°F (66°C), and the oxidation rate doubles for every 18 to 20°F (10 to 11°C) rise [³, p. 16].

Watch these points:

• Barrier overflow pipe. On a liquid barrier, oil spilling from the overflow pipe after a few hours at system temperature indicates impending seal failure. Replace the seal before leakage becomes excessive [³, p. 20].
• Initial heat-up. A small amount of barrier oil during initial thermal expansion can be normal. Monitor it. It should not increase over time [³, p. 20].
• Nitrogen barrier. The 3/8" connection at the bottom of the bearing housing stays open as the nitrogen outlet and the seal leak detection point [³, p. 16]. Nitrogen pressure is regulated to 1/4 psig (1.72 kPa) maximum [³, p. 16].
• No barrier. With a non-oxidizing oil, a collection pan under the drain opening catches condensed vapor or seal leakage as the faces wear [³, p. 16].

Common causes to correct before the rebuilt pump goes back in service: running dry [³, p. 19], operating at low flow or shut-off [³, p. 19], misalignment, which reduces seal life [³, p. 13], and pipe scale or weld debris reaching the seal faces [³, p. 13].

What to inspect at teardown

Follow the full disassembly and safety sequence in the RA IOM [³, pp. 26–30]. On hot oil, these steps matter most:

• Do not begin work until the pump and its contents are at ambient temperature and atmospheric pressure [³, p. 27, warning].
• Lock out and tag out the driver, the suction and discharge valves, and every sub-system [³, p. 27, steps A–C].
• Drain the barrier oil and any other sub-system fluids into separate containers [³, p. 27, step E].
• Bleed remaining pressure through a valved drain to a closed container mounted below the pump [³, p. 27, step G].
• Loosen the casing nuts only one full turn, then break the gasket with the two jackscrews in the bearing housing flange. Fluid or pressure can still be trapped behind it [³, p. 28, step I].
• Support the rotating unit with lifting equipment as you pull it from the casing [³, p. 28, step J].
• Never apply heat to remove the impeller or any other part. Trapped vapor could cause an explosion [³, p. 4; p. 29]. Do not drill, saw, cut or hammer parts to get them off [³, p. 29].
• Expect to feel the mechanical seal spring release as the shaft comes out of the bearing housing [³, p. 29, step F].

At teardown, check:

1. Casing (5). Inspect for wear, corrosion or other damage [³, p. 28, step M]. Some sizes use a casing ring (6A) pressed into the casing [³, p. 9; p. 33, step AA].
2. Casing gasket faces. Remove all Grafoil down to clean metal on both the casing and bearing housing without damaging the faces [³, p. 28, step L].
3. Old shaft (29). Two lip-seal contact wear patterns under the front grease seal, or scoring under the radial bearing (180), mean the shaft must be replaced [³, p. 30, step A]. With a kit, the shaft is replaced anyway. The old shaft still tells you how the pump was running.
4. Fan (120). Do not bend the blades during coupling and fan removal [³, p. 27, step D; p. 29, step B]. Wear gloves; the fan is thin metal and can cut [³, p. 29].
5. Radial bearing bore. The bearing housing (26) is not in the kit. Its bore must accept the replacement cartridge and seat it against the shoulder [³, p. 30, step C].

Press the radial bearing out and back in

Our best practice on RA3146 rebuilds is to press the old radial bearing cartridge (180) out of the bearing housing and press the kit cartridge in. Do not reuse the old cartridge. The IOM covers both steps.

Out [³, p. 29, step K; p. 30, step K2]: The RA3146 cartridge has two 3/8"-16 UNC tapped holes, reached from the impeller end of the bearing housing. Bolt a 1/2" Class 300 flange securely to the cartridge, with washers on the bolts. Use a 14" length of 1" pipe (1-5/16" OD), cut square on the ends, to reach down through the bearing housing and press the cartridge out. After the cartridge is out, remove and discard the 3/8" seal vent plug [³, p. 30, step L].

In [³, p. 30, step C]: Press the kit cartridge into the bearing housing until it seats firmly against the shoulder. Install it with the two tapped holes facing outward and the 1/8" through hole at the top of the bearing housing. Use a press with a pad over the end of the cartridge. Never hammer on it; the carbon bearing can break. If no press is available, the IOM allows pulling the cartridge in with threaded rod through the housing, with a large washer and nut on each end.

When the shaft assembly goes in later, keep the shaft end from striking the carbon bearing [³, p. 32, step N].

Reassembly with the kit shaft

The kit shaft replaces IOM steps D through M. From there:

• Install a replacement seal vent plug in the top of the bearing housing. Use no sealant and leave it loose; it comes out again for venting [³, p. 30, step B].
• Lubricate the bearing housing bore so the gland O‑rings (325) slide in undamaged. Slide the shaft assembly in from the end cover end without striking the carbon bearing [³, p. 32, step N].
• Fit the end cover gasket (77B) [³, p. 32, step P]. Press the rear grease seal (76A) into the end cover from the bearing side, up against the shoulder (replacement shaft) [³, p. 32, step Q].
• Lubricate the shaft where 76A rides and put grease around the exposed bearing face. Fit the end cover with the plugged hole toward the baseplate. End cover bolts: 20 lb-ft (27 N·m) [³, p. 32, step R].
• Fan collar mark: 3-1/4" (83 mm) from the coupling end. Fan concave side ("PUMP SIDE") toward the pump [³, p. 32, step S].
• Coupling hub flush with the shaft end [³, p. 33, step T].
• Impeller bolt: 60 lb-ft (81 N·m), holding the shaft by the coupling hub flats [³, p. 33, step Y2].
• Casing stud nuts (3/4" studs), with a replacement casing gasket, tightened slowly and evenly: 105 lb-ft (142 N·m) [³, p. 33, step AB]. Before this, back the jackscrews out so they do not protrude on the casing side [³, p. 28, step J].
• Turn the shaft by hand with heavy gloves to check for rubbing, after assembly and again after bolting down [³, p. 33, steps AC and AE].
• Alignment within 0.002" TIR [³, p. 13], checked again hot at operating temperature [³, p. 12, item 7; p. 13] and after about 200 hours [³, p. 12, item 8].
• Before start-up: vent the seal chamber, fill the barrier and remove the bearing grease relief plug from the end cover [³, p. 21, items 3, 10 and 13; p. 16].
• After 30 minutes of running, stop the pump, top up the barrier, refit the grease relief plug and tighten it to 7 ft-lb (10 N·m) [³, p. 20]. Refit the coupling guard with the expanded metal nearest the motor [³, p. 20].

Follow the RA IOM for the full repair procedure. You can find it in Tusk Industrial's product literature library.

Confirm fit before you order

The IOM asks for the pump serial number and size when ordering parts [³, p. 21]. The serial number is on the nameplate and is also stamped on the suction flange or the top edge of the bearing housing front flange [³, p. 21]. The nameplate record also includes "Impeller Diameter Installed" [³, p. 2].

On the RA, pump size and actual impeller diameter drive parts selection. The serial number matters less. Do not trust the nameplate diameter alone. In our experience, OEM heater builders often order full-size impellers and trim later without restamping the tag. We see pumps tagged 8.5" with a 7.5" impeller in the casing. Measure the impeller.

Then confirm the casing family. Every 8.5" size uses kit 6138148, and every RA3146 10" size (1.5x3x10, 2x3x10, 3x4x10 and 4x6x10 #2) uses kit 6138149 ². Diameter alone can mislead. 8.5" family impellers trim down to 5.50" (6.00" on the 4x6x8.5), and 10" family impellers trim down to 7.00" (7.50" on the 4x6x10 #2) ². A 7.5" impeller fits inside both ranges, so it could be in either casing.

The flanges won't settle it either. The 1.5x3, 2x3, 3x4 and 4x6 each come in both an 8.5" and a 10" casing with the same ANSI Class 300 RF flange sizes. Read the full model on the casing or pump nameplate, check the casing casting marks, or measure the casing. Confirm suction by discharge by casing before you order.

Kit and pump pages:

• Dean RA3146 8.5" Repair Kit 6138148
• Dean RA3146 Pump

Questions

If you are not sure which kit fits your pump, or want help with a rebuild, call us at 888-341-7085 or visit pumpresource.us.

Sources

1. Dean RA3146 8.5" Repair Kit 6138148, https://pumpresource.us/dean-ra3146-8-5-repair-kit/
2. Dean RA3146 Pump, https://pumpresource.us/dean-ra3146-pump/
3. Dean Pump Series RA Installation, Operation, Maintenance Manual, TUSK-IOM-DEAN-RA-001, Version 1.0, Tusk Industrial, https://www.tuskind.com/wp-content/uploads/2025/10/Tusk-Dean-RA-Pumps_Version-1.0_May-2026.pdf