View Full Version : Coolant Radiator Blueprint 347 extra 5/8 in port open
MichaelD_MK5
02-21-2026, 11:29 AM
All was going well today filling the cooling system on MK5 until coolant started pouring out a 5/8 in port on the front of the BP 347 engine (Pic 01)225845. What should this extra port go to? I thought I saw someone attach a hose and bend it over to cap it. Is that correct?
MichaelD_MK5
02-21-2026, 11:33 AM
I think this is for a heater return but I'm not using a heater so I still think cap it.
Mike.Bray
02-21-2026, 12:05 PM
For a heater hose. Cap it.
Jeff Kleiner
02-21-2026, 03:47 PM
After having seen failures I don't trust those rubber caps so I remove the nipple (most easily done by crushing it into itself) and either install a freeze plug or tap it for a pipe plug.
Jeff
If you choose to cap it, these are better than the typical caps you'll find.
https://www.amazon.com/dp/B083QJNNBY?ref_=ppx_hzsearch_conn_dt_b_fed_asin_ti tle_10&th=1