737 Jock

Extremely quick cabin warm-ups are one of the benefits of the Acura turbo-charger system. On cold starts the coolant runs in a bypass circuit that eliminates the radiator, and takes full advantage of the hot exhaust.

The circuit begins in the engine block with coolant heated by the cylinder jackets. It is then pumped separately to the very hot exhaust manifold and turbo-charger housing. Hot coolant exiting the exhaust and turbo is rejoined at the water outlet mixer which pipes it directly to the cabin heater -- you get warm air within minutes of start.

(Liquid cooled exhausts are seen mostly in watercraft, not cars -- domo arigato Soichiro Honda.)

Bypass lines from the cabin heater and water outlet mixer go straight back to the water pump where it re-enters the cylinder jackets again. The temp reading you see rising so quickly on your multi-info-display is taken at the water outlet mixer on the cylinder head, not the radiator. The bypass circuit runs until the thermostat opens (at about 170F) and coolant is sent through the radiator.

So, does this near instant heat and temp reading mean you can go boosting your RDX after a cold start?? NO!

Oil plays an important role in engine and turbo lubrication and cooling. Oil is engineered to be most effective at normal operating temp (230F). Even though the coolant seems warm, the thicker oil requires more time to heat up. After a winter start, minimize throttle and boost for 12 to 15 minutes to protect your engine. (In the summer about half that should do.)

On shutdown oil tends to coke (burn) onto the turbo shaft if a turbo is too hot. The RDX has no after-run coolant pump or turbo timer to cool the turbo-charger -- however coolant continues to circulate through the exhaust manifold and turbo housing by a clever convection method. You can help turbo cooling by avoiding boost just before shutdown. Try to keep the engine near idle for the last minute or so. Don't race the guy in the Dodge Nitro for that good mall parking space -- let him have it -- he's got enough problems.

MakTypeR

Good to know..thanks.

Pacer

Aye, good info, thanks for posting.

mau108

Hey 737 Jock nice tid bit of info there. Sounds like your a honda/acura rdx trained technician :P (or you just have the RDX Bible on hand :P)

Was wondering if you see the RDX having any advantages to an oil catch can. I noticed on my NA prelude that it does get quite a bit of oil in there so I'm assuming the RDX should have alot of oil recirculating.

Also anyone know where the PCV is on the RDX? I haven't really looked around but its not at the usual spots of engines.

737 Jock

The PCV valve is located just below and inboard of the power steering pump. The hose runs forward and elbows into the intake manifold.