Radiator drain plug difference

[abscate]

Plug it up with JB Weld and screw it in with some Teflon tape. All good.

Thanks for reminding me to pull the old one of Shagg, too.

[MrAl]

I broke the drain plug in a 98 v70 with what I assume is it's original radiator. I was able to get it out easily with a screw extractor, but when I went to put the spare one in, it kept dripping out of the drain hole. I tightened it up a little bit past my comfort level and it kept dripping. I compared the replacement to my spare and found the original had an o ring mounted further up the plug itself, and overall slightly different design. 20231108_115738.jpg
98 v70 that I broke is on the top. The spare one I had is on the bottom. The spare came out of a radiator from a 94 850, and looks the same as all the replacement parts I see online.

Has anyone come across this? Difference in radiator OEMs or possibly replacement vendors?

Hi there,

I can tell you almost for sure that the radiator is aftermarket and so probably not very standard as far as Volvo goes.
The shop that replaced that radiator would never have sprung for a genuine Volvo radiator. They buy aftermarket stuff and sell it as if it was genuine Volvo. The guy that owned that shop finally retired a few years ago.
I am not sure if I would be able to get ahold of him and his notes to find out where he got the radiator but when I am feeling better I could ask around. I am guessing, just guessing, it was from Napa, as I know he used that place for parts, but not sure if all parts.

[jsrnsis]

I couldn't find anything for NAPA radiator drain plugs, I don't know why they'd make it so close to the correct Volvo plug but not the same size.
Anyways I found the size was an M12 with a 1.75 thread pitch, plastic bolts are available online or from supply companies like McMaster Carr.

[MrAl]

I couldn't find anything for NAPA radiator drain plugs, I don't know why they'd make it so close to the correct Volvo plug but not the same size.
Anyways I found the size was an M12 with a 1.75 thread pitch, plastic bolts are available online or from supply companies like McMaster Carr.

Hi again,

Oh that's great to hear also.
So are you getting close to solving all these problems now, or a lot to go yet?

[jsrnsis]

I couldn't find anything for NAPA radiator drain plugs, I don't know why they'd make it so close to the correct Volvo plug but not the same size.
Anyways I found the size was an M12 with a 1.75 thread pitch, plastic bolts are available online or from supply companies like McMaster Carr.

Hi again,

Oh that's great to hear also.
So are you getting close to solving all these problems now, or a lot to go yet?

Getting closer, this radiator drain plug is probably solved, I'm going to stick the rubber gasket out of a garden hose under the head of the bolt and use some teflon tape to make sure it seals. The bolts need to be cut to under half their length to fit snug in the radiator.

Edit: https://www.amazon.com/Biaungdo-Nylon-P ... 321&sr=8-1 these are what I used, just make sure to use the MVS Amazon link when you buy them, i don't know how to link it through the referral. When you go to cut them just use a hacksaw and not a Dremel cut off disk, or you'll end up flinging melted nylon all over the place.

[TrevB]

I have the exact same issue, and I’m sure the top plug is from an aftermarket rad, and here’s how I know.
I bought a new aftermarket rad from a local auto parts store and installed it without an issue. However, after filling up the system with coolant and running it, I noticed a VERY slow drip forming at that rad drain petcock. I figured maybe it was loose from the factory, so I tried to snug it up…… and it twisted right off with barely any pressure. Maybe it was broken or weakened from shipping damage, I’m not sure, but it basically it fell apart with minimal effort.
Just as you did, I easily removed the threaded portion with an easy out, and I figured that I could just use the one from the old OE rad. But when I removed it and compared the two, they looked IDENTICAL to the ones in your picture. The top one came from the aftermarket rad, the bottom from the OE. The thread pitch is slightly different as well, which you can also see in your pic.
The brand of the aftermarket rad I bought is Pacific Best Inc. and I’ll be reaching out to them and asking if there’s any way I can get my hands on one of the petcocks they use. I guess if they tell me I can’t, just like you I’ll be trying to figure out a thread pitch and finding a solid plug that will fit in that port.
If I have any luck, I’ll post again with a part number!

[abscate]

Just plug it with JB Weld , after getting it clean and dry, and use the lower rad hose for drains. I like the functionality of a drain petcock but not the flow rate.

[jsrnsis]

I have the exact same issue, and I’m sure the top plug is from an aftermarket rad, and here’s how I know.
I bought a new aftermarket rad from a local auto parts store and installed it without an issue. However, after filling up the system with coolant and running it, I noticed a VERY slow drip forming at that rad drain petcock. I figured maybe it was loose from the factory, so I tried to snug it up…… and it twisted right off with barely any pressure. Maybe it was broken or weakened from shipping damage, I’m not sure, but it basically it fell apart with minimal effort.
Just as you did, I easily removed the threaded portion with an easy out, and I figured that I could just use the one from the old OE rad. But when I removed it and compared the two, they looked IDENTICAL to the ones in your picture. The top one came from the aftermarket rad, the bottom from the OE. The thread pitch is slightly different as well, which you can also see in your pic.
The brand of the aftermarket rad I bought is Pacific Best Inc. and I’ll be reaching out to them and asking if there’s any way I can get my hands on one of the petcocks they use. I guess if they tell me I can’t, just like you I’ll be trying to figure out a thread pitch and finding a solid plug that will fit in that port.
If I have any luck, I’ll post again with a part number!

I bought a big bag of plastic bolts that I linked earlier that matched the thread pitch and placed a 3/4 garden hose rubber washer under the head after cutting down the bolt. It worked drip-free, but sadly the car is no longer with us.

I don't know if me shipping you one of the bolts from NY or you ordering your own would be cheaper. M12x1.75

[TrevB]

I appreciate that! But I’m in British Columbia, Canada, so I’m sure the shipping wouldn’t make sense. Thank you very much for the info though!

[TrevB]

Left plug: From OE Volvo Rad
Right plug: From Aftermarket Rad

So, small update to what I’ve found…..
The threads on the drain plug for the OE rad are in fact M12-1.75. However, the threads in the aftermarket rad are NOT M12-1.75. After reading your post, I sourced a M12-1.75 plug locally for this aftermarket rad and tried to put it in. It tightened up about two turns in and I didn’t force it out of fear of splitting the threaded hole. After pulling it back out and comparing with the broken drain plug, the threads are definitely different. I did mention that before about your original pic, that I thought the threads looked different, but I trusted your confidence and went with the M12-1.75 plug.
Maybe the fact you did it with plastic bolts made the difference, or maybe it’s a different aftermarket rad, I dunno….but after using a thread gauge I can 100% confirm that the threads in my aftermarket rad are not M12-1.75 like the OE Volvo rad threads are.
Back to hunting for the proper threaded plug tomorrow I guess……now starting to wish I just did the JB Weld suggestion…hahaha.