2004 Accord 2.4L - Vtec mystery solenoid/sensor o-ring leaking
 

2004 Accord EX auto
2.4L k24
~230k miles

Old accord here which runs great, but I have a leak on my vtec spool valve/actuator assembly. I've already replaced the gasket (15815-RAA-A02) as well as the (13x1.5mm) o-ring on the oil pressure sensor that screws into the top of the spool assembly. Despite this, I still have an oil leak coming from the top of the spool assembly from what looks like a barrel shaped mystery solenoid of some kind. It's held in by a bolt with an E8 (e-socket) head and there's an o-ring underneath. Honda doesn't identify it separately in the schematic/part list for the vtec spool assembly, so they don't show any part numbers or give any indication of what the o-ring size is.

It seems a little odd that honda doesn't have this part or the o-ring listed separately. I took some measurements and it appears the o-ring is about 18x1.5MM but it would be a shot in the dark to replace it. I'd hate to replace the whole assembly just for a silly $1 o-ring.

Has anyone run into this problem before and find the correct o-ring size?

https://cimg3.ibsrv.net/gimg/www.hon...e872ac74f1.jpg
leak location
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solenoid removed. o-ring not shown.(junk yard unit)
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Solenoid not shown separate.

No option but to try a replacement based on your measurements. Seal appears to be based on longitudinal compression so key measurement is oring thickness. Too small will not get enough compression to seal.

good luck

I ordered some 18x1.5mm Buna 70s (BN70) orings I'll report back how they work if they work. Fingers crossed the /thickness cross-section is thick enough.

Update: I got in the 18.x1.5mm Buna-N 70 orings and tried them on my car after taking the vtec spool and solenoid off. The o-rings fit in outer edge of the o-ring slot (barely), however they didn't seem thick enough - it would have been up in the air as to whether it sealed. To go thicker in Cross Section would of meant it would be too big for the slot - so I had to use a completely different o-ring.

The old o-ring was totally harden, flat, and hard to measure.

I ended up using an oring from a generic o-ring kit in a clear plastic case I had laying around. The size listed was 5/8"(ID) x 13/16" (OD). Which works out to .625" x .8125", and the cross section is approximately .10". The metric measurements would be 15.875mm (ID) x 20.6375MM (OD), 2.54mm cross section. After rounding, I'd guess a 16x2.5mm Buna-N 70 would be close the same size if you can't find a 5/8" x 13/16".

The oring diameter was just right for the slot. I might have been able to even go a little thinner if needed. I bolted the solenoid down to the vtec spool assembly by hand and put everything back together. It's been almost a week and a few hundred miles of driving and.. No Leaks!


Sides notes if your going to do this:
-Get a spare gasket (15815-RAA-A02) for the vtec spool assembly as you can't remove the bolts for the vtec solenoid itself without removing the whole assembly. The head is in the way of getting one of the E8 bolts out.
-Also, if you don't have an impact wrench - loosen one of the E8 bolts by hand before removing the vtec spool assembly from the head. The bolts are tight and loosening them without it being bolted down is pretty hard.
-Clean the whole area around the solenoid before you remove it as there is a lot of dirt and grim that you don't want getting in the solenoid, etc.

https://cimg8.ibsrv.net/gimg/www.hon...ad775ccb05.jpg
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thanks for update.

good luck