VW to NAPA Part Number Coolant Hose Conversion Chart

VW to NAPA Coolant Hose Conversion
for many ’86-’91 Vanagons
By Darrell Boehler

This conversion is based upon NAPA brand hoses that were either exact replacements for, or adapted to replace their VW counterparts. The conversion was performed on a 1986 VW Vanagon Westfalia with 2WD, manual transmission, and air conditioning. Your mileage may vary.



Coolant Hoses
Wasserboxer 86-91 2WD


Heater hoses are all 5/8″ hose and no big problems. I replaced the T’s for the rear heater with 5/8″ diameter T’s on all three points because the originals had two 5/8″ and one 1/2″ point. 30′ of 5/8″ hose is needed to replace all heater hoses. Straight hoses will even make the turns for the front heater under the dash without too much problem. However if your inside front heater hoses are good I would consider keeping them as they require a bit of time to replace. I was considering connecting my heaters in series instead of parallel, but backed off because I thought it might degrade the heat. NAPA has regular grade or premium grade heater hose and so do many other stores.

Simple Conversion



VW Part #: NAPA Part #: Description: Dimensions:
D N902873.03 1.5″ hose* Valve to radiator feed.
251-121-058a 1″ hose* Thermostat housing to valve. 1″ ID about 2ft long
G 443-121-107A This is a 7mm hose from a VW FLAPS, NAPA here doesn’t carry 7mm hose
H 252-121-130b 7990 Right head front to valve.  1″ ID, 6″ long. Has 2 60 degree bends
J 025-121-058e 10050 Thermostat housing to oil cooler pipe .472″ ID one end, other end .635″, 3″ long
025-121-058D Oil cooler to oil cooler pipe from from thermostat housing. No direct solution here. However 5/8″ heater hose about 2 feet long can be run directly from the oil cooler to the thermostat housing eliminating the need for hoses J and K. I like the one hose solution better than the normal path as there is more clearance from the oil cooler hose and the header pipe. My hose K got brittle and blew coolant all over my clean engine.
025-121-058G Oil cooler to oil cooler pipe from water pump. No NAPA hose replacement and no good way to eliminate this hose that I have found. Maybe someone else can find a sub.
025-121-058J 3/8″ ID hose A straight hose will function fine here 3/8″ ID 4″ long
O N901287.03 1″ hose* Water pump feed to right side of crankcase. 1″ ID 3″ long
443-121-107A 7mm VW FLAPS. Right head to pipe
025-121-108D No NAPA solution. Pipe at water pump to expansion tank. This hose is designed to take a lot of flexing between the engine and the expansion tank. I need help on this one, somewhere there must be another application that uses a similar hose. 1″ ID one end, 3/4″ ID other end
R 025-121-058h 9807 Expansion tank to pipe tee .620″ ID both ends. 90 degree bend each leg 4.5″ long
S 025-121-058B No NAPA solution. Thermostat housing to pipe tee. Need help on this one also. 1/2″ ID one end 7mm other end, about 14″ long.
? 025-121-073H 777 Thermostat housing to water pump pipe. This hose doesn’t seem to be listed on the chart. Good picture of it in Bentley on 19.11. It is the big one there with the 90 degree turn. 1.5″ both ends 90 degree bend 1 leg 6″ other 4″


* I got a 3ft long heavy duty NAPA hose and cut it to fit

For the rest of the hoses I used copper pipe, 90 degree elbows and various copper pipe adapters. This requires soldering some pretty heavy pipe but could be done with a plain propane torch. I bought NAPA heavy-duty hoses that are used mostly on diesel trucks and industrial applications. This was a mistake I would go with regular grade hoses if I did this again. The heavy-duty hoses has double layers of nylon reinforcement and outside wrapped with nylon. It is a real pain to work with and after a couple of days working with them I discovered why most Illinois diesel mechanics appear to be fresh off the Minnesota and Wisconsin farms. I used 6′ of 1.5″ ID hose, 3′ of 1.25″ ID hose, 3′ of 1″ ID hose. Most 1″ stuff was used in the previous table on F and O.

Complex Conversion



Hose: VW Part #: NAPA Part #: Description: Dimensions:
A 251-121-082 1.5″ and 1.25″hose Upper radiator feed hose Radiator connection is 1.33″ and long hoses are 1.5″, straight 28″ long. I used some 1.25″ hose at the radiator end and made an adapter using 1.25″ copper pipe, adapter to 1.5″ copper some 1.5″ copper pipe then 1.5″ hose to the long feeder hose.
B 251-121-083H 1.5″ and 1.25″ hoses Lower radiator return hose Same ID on hose as A above however 3 90 degree elbows are required on this one. Use a short 1.25″ hose, a short 1.25″ pipe, 90 degree elbow toward the rear a short 1.25″ pipe (make this pipe just long enough to get aft of the radiator and radiator holder bracket), 90 degree elbow pointing up and slightly to the left, enough 1.25 pipe to get up high enough to get over the spare tire, a 1.25 90 degree elbow pointing toward the rear, some 1.25″ pipe, an adapter to 1.5″, some 1.5″ pipe then 1.5″ hose to the radiator return long pipe.
E 025-121-062E 1.5″ hose and some 1.5″ copper pipe Return to thermostat housing 1.5″ both ends however this one goes up and over the transaxle. Use a short 1.5″ ID hose about a 2.5 inches of copper 90 degree up, about 10 inches (check this measurement) 1.5″ ID copper pipe up line these up so your copper pipe rests nicely in the hose holder above the transaxle), Now 90 degree copper elbow and you are heading over the transaxle, install enough 1.5″ copper pipe so you line up with the thermostat housing. (hint it is best to be a little too long with the pipe going over the transaxle or your hose might cause shifting problems). Now turn 90 degrees with copper elbow toward the thermostat housing install a short 1.5″ ID pipe in the elbow. use a 1.5″ ID hose to connect to the thermostat housing. That sounds pretty involved, try this for directions from the long return hose go back a few inches up about 10 inches over the transaxle about 20 inches and turn back toward the thermostat. What you end up with is a copper pipe with three 90 degree elbows attached.
N 025-121-058M Gates 20693 hose, home made adapter and some 7mm hose Left head to pipe One end is 1″, the other is 7mm. Start with a Gates 20693 hose (which is a 1″, 90 degree hose). I then used an adapter from my local hardware store from 1″ down to 1/4″ ID copper pipe that I used and then just stuffed the 7mm hose over that. The original hose on my 86 had sprung a leak and for a while I thought I had a head leak. Thanks Malcolm Stebbins.