Subaru is giving me the wrong part number for the radiator cap for my car

I have been trying to replace my radiator cap for about a month now.
I have a 2005 Subaru Legacy GT Ltd. (Bought in 2004). Subaru tells me the part number is 45137AE00B (this is the one that goes on the external reservoir (not the overflow tank).

parts.subaru.com tells me the part number is 45137AE00B, I bought this, and it does not fit.
The old main seal is 30.5mm diameter, the new seal is 27.9mm in diameter. The new seal slips past the seat and the spring does not get compressed when the cap is installed.

I also tried to buy a 3rd party part from O'Reilly Auto parts. They sold me a Murray 7516. This also does not fit. Its even worse because the rubber seals are thinner.
All other online retailers I've tried tell me to buy the same Murray 7516 part.

SubaruParts.com and SubaruOnlineParts.com both have a broken parts seach. None of the diagrams they show even show the tank that this radiator cap is on. When I finally found the part number elsewhere, they showed this cap on the radiator, but that one is part number 45137FE002 (This part fits properly there, I bought this one too)

What is the correct part number?

45137FE002

Think this what you're looking for.

Try parts.subaru.com

http://parts.subaru.com/p/Subaru_200...5137FE002.html

Shadow is right, 45137FE002 is the cap for the radiator.

Note the Expansion Tank (up by the turbo) uses a different cap from the Radiator! Because they look alike and fit alike it is common to reverse them or replace a defective one with the wrong cap. There is a difference!
If you get them wrong it can lead to weird cooling issues that will drive you insane trying to track down what the problem is. If you have cooling issues the first thing to do is check you have the right cap in the right place.

Be wary of aftermarket performance radiator caps with a higher bypass.

For example Mishimoto states clearly that you do not use the 1.3 bar cap supplied with their performance radiator for the radiator!

Here's what they say:
"Included 1.3 bar radiator cap raises the boiling point of engine coolant to provide a safer and more efficient system"

But then the fine print!
Caution

The provided Mishimoto radiator cap should replace the stock cap located on the expansion tank. The stock cap attached to the radiator should be installed on the Mishimoto Performance Aluminum Radiator. The Mishimoto radiator cap is a two way valve, while the stock radiator cap is a single valve. Due to the difference in construction, the Mishimoto cap cannot be used on the radiator. If the Mishimoto cap is fit on the radiator, overheating may occur.

And to confuse you they show the supplied high pressure cap ON the radiator!



https://www.mishimoto.com/subaru-wrx...diator-01.html


This is what the Expansion Tank OEM Cap looks like. It has "Ears" and marked 108 KPA. Part Number: 45137AE00B. I'm 99.9% sure you can also use the WRX/STI cap: 45137AE003




This is the Radiator Cap. No "Ears" and marked 137 KPA: Part Number 45137FE002



You can remember them because Subaru wants you to fill-flush-service thru the expansion tank so that cap has Ears. They don't want you to use the Radiator cap so it has no ears.

Originally Posted by Infosecdad

Try parts.subaru.com

http://parts.subaru.com/p/Subaru_200...5137FE002.html

Shadow is right, 45137FE002 is the cap for the radiator.

This is the part that goes on the radiator. I bought this and it fits on the radiator. The problem I am having is with the other one, the one that goes on the external tank, the one with ears.
The original and the replacement look the same, except for the disk of rubber on the original is bigger than on the replacement. The original needs to be pressed down to compress the spring to install, the replacement only needs to be placed on the tank and rotated to tighten. It is as if the spring loaded seal is not engaging at all.

Originally Posted by DAP

This is the part that goes on the radiator. I bought this and it fits on the radiator. The problem I am having is with the other one, the one that goes on the external tank, the one with ears.
The original and the replacement look the same, except for the disk of rubber on the original is bigger than on the replacement. The original needs to be pressed down to compress the spring to install, the replacement only needs to be placed on the tank and rotated to tighten. It is as if the spring loaded seal is not engaging at all.

Apologies, your first sentence was "I have been trying to replace my radiator cap for about a month now." and that was the radiator cap.
Looking up the part number for the overflow matches what you were told (45137AE00B).

I have an '05 as well (build date of 02/05), the inner metal part of my expansion tank cap is 29.05mm and it hasn't been replaced as far as I know. The rubber seal on the end is slightly bigger than the inner metal part and I think that is expanding over time.

If the dimensions of your inner metal part is the same as mine, I'm wondering if the difference is the rubber seal part just expanding with age.

I have added pictures of the radiator caps I bought vs the original.
1st picture is murray on right, second is replacement subuaru on the right.

Is the diameter of the metal part behind the rubber the same on the replacement caps as your original one?

Can confirm 45137AE00B fits, I replaced both my caps a few months ago with OEM due to the odd cooling issues Sgt.Gator was talking about.

When you say is doesn't compress, are you saying that it slips entirely through the lower hole into the tank or just isn't as tight? Mine wasn't hard to put in, and it's holding pressure just fine.

Can someone describe the symptoms of the weird cooling system issues you would see if the caps were not correctly installed? Sgt.Gator?

In my case, loss of coolant. Air kept getting into the system and I couldn't find a leak. Then read the part of the FSM covering radiator caps, and realized what was going on.

Miles, besides what UTC-Pyro said, you can get overheating. Some guys have chased their tails replacing thermostats, water pumps, radiator flushes, thought they had air pockets trapped in the lines, all because of the wrong caps.


Dap you have me curious now. Sunday I'll compare my Mishimoto cap, Spec B cap, and STI cap, then get back to you.

Originally Posted by Infosecdad

Is the diameter of the metal part behind the rubber the same on the replacement caps as your original one?

I think so. I'll measure it when the engine cools.
Update: Yes they are the same diameter.

Originally Posted by utc_pyro

Can confirm 45137AE00B fits, I replaced both my caps a few months ago with OEM due to the odd cooling issues Sgt.Gator was talking about.

When you say is doesn't compress, are you saying that it slips entirely through the lower hole into the tank or just isn't as tight? Mine wasn't hard to put in, and it's holding pressure just fine.

The seat seems conical, so a smaller seal would fit down lower.
I think it may seal, but it certainly won't hold 15 PSI.
I drove the car with the new cap installed, my radiator fluid was still boiling.
If at least sucks the overflow fluid back into the radiator, it will be an improvement over the state of the original cap.

Part of the problem is that I was trying to determine where the leak is in the radiator system. Trying to narrow down the location by replacing the cheapest part 1st, but with the part not matching the original, and the fluid still boiling, I have not narrowed down the problem at all.

I'm mostly suffering an air leak, air being sucked into the radiator as it cools rather than radiator fluid. If there is a leak somewhere other than the caps, it is very small and I have not seen evidence of it yet.

Originally Posted by DAP

The seat seems conical, so a smaller seal would fit down lower.

Odd, is your coolant tank aftermarket? Mine has a wide flat seating surface that the rubber seats with. The "conical" portion of it is just the radiused edges of the hole going from the neck into the tank.

But the unfindable air leak was my issue. Was completely resolved by cleaning the seats and switching back to oem caps (had mishimoto on radiator that came with it).