If your G37 is getting older, and in the 100K miles I would recommend replacing the heater hose connector on the passenger side. Luckily I caught it in time before the plastic heater hose connector broke in half, I had coolant dripping everywhere. I only replaced the hose connector since the hoses were in good shape and I used Dorman 3/4 inch straight heater hose connector (part number: 56430). When taking the hoses out, you do not need to take the hose out that connects to the back of the engine it is just a hassle, only remove the hose that is connected to the back of the firewall. After removing the hose just squeeze the tube, and the plastic connector will just fall apart, then place the Dorman. For the hose that is connected to the back of the engine, there is enough room to grab the hose and face it down, and you can just squeeze the tube and all of the pieces will fall out. Make sure to keep it facing down until all of the pieces come out, you do not want any of it getting stuck. You can also close off the tube with some pliers just to be 100% sure that none of the plastic pieces go inside. After that just connect the hose to the firewall side, then join the two connectors. You will have to drain the coolant and then refill it. To make it easier to get the clamps out use 11 inches, 90-degree pliers.






The broken plastic connector

After replacing it with the Dorman connector

 

Thanks for the pics.

Hassle yes, but if you're already in there, 100K ,miles, replacing the hoses would be a good idea🤔.

 

Yes, if you already have the hoses you can replace them. I have had a few cars with 200k miles with OEM hoses and never had issues, the only things that tend to go out is the hose clamps. They tend to lose their tension and cause small drips. But, I rather have small drips than have a hose connector snap in half, because once it snaps you lose all of your coolant instantly.

 

Generic question (may have been asked before), but is the connector even necessary?

I know I will be tackling this project in the fall with all new hoses, but was wondering if those couplers are needed or would it be better to just straight plumb the hoses? The less connections/clamps, less likelihood of potential leaks. Just thinking it loud...

 

^^Good question. Maybe they did it to reduce cost of hose production - fewer bends = easier to make, cost less.¿?

 

Yeah this is a good PSA. I would also say just get the Z1 metal replacement with the bleeder, it makes bleeding the system much easier once you replacing the coupling. That stupid coupler left me stuck on the side of the road.

 

You can, but it will be pretty hard to find a hose with the correct bends to connect it from the back of the motor to the firewall. If you use a generic tube the hose will pinch at some areas. I am surprised Z1 did not try to create that actually.

 

Thanks all for the information. I already have the scheduled for the spring and after I have acquired all the hoses and fittings. My G has original hoses at 130K and I'd just as soon not be stranded due to my own negligence iCrap, you say that Z1 has a replacement hose fitting with the bleeder? Is this the same fitting as the Dorman fitting at the top of this thread?

I can see this job is going to require some gymnastics to complete given the close proximity of the engine to the rear firewall. Other than what Said Amir posted, any tips/tricks/curse words that help in this?

 

Z1 has two types of this connector:


But for $34 I think they are serious overkill.

I just used a simple ¾" barbed brass fitting

that I bought from Home Depot for ≈$5 and called it a day.

 

Thanks for the info ILM-NC G37S I do agree that Z1's parts look like serious overkill as I already have a bleeder screw in the system. I'll probably opt for the Home Depot or Dorman options instead

 

14mm 3/8s deep socket for the chrome look

 

I keep putting this off and I know I'm going to regret it soon as I'm at 95k currently. I used a coolant exchange machine when I did my coolant service last year so I didn't need to bleed the system but from what I gather using the OEM bleeder in front of the driver side air box is a PITA compared to Z1's "easier to access" bleeder port. I have also read the O-ring on the Z1 bleeder port dries out prematurely so some users upgraded to higher quality O-Ring during the initial install. Aftermarket parts for you, more complexity more potential problems...sounds like most German cars actually lol.

 

Does anyone have the part # for those two hoses? Should replace the hoses as well. Just can’t find those part #s

 

92401-JK20A (from connector to firewall (heater core)) ≈$10;
92402-JK20A (from engine to connector) ≈$12;
92417-JK20A (connector) for those who insist on using plastic ≈$14 (I used a ¾" brass barb fitting that I paid ≈$5 for)
01558-00521 clamps (need 4) ≈$11.20 EA. (much cheaper on eBay)

92400-JK200 is a kit that has the "front hose" with the connector pre-installed ≈$17
(all prices above estimated/quoted from http://www.discountinfinitiparts.com as of 31 Jan 2022.

There is a seller on eBay who has the whole kit (both hoses + connector (no clamps)) for $41.

 

@ILM-NC G37S my fellow North Carolinian, thx for the information. Your posts are always informative and timely. Thank you