Oil Pressure drop on warm up ?
Finally,got my 1984 Gtv6 To start after sitting for 10 years . Starts runs great 55lbs pressure....then when it warms up 180 or so ...oil pr. drops middle rpm knocking sound....good oil...is it the obvious wore out engine...or? Help Do I need to blow the dust off the old milano 2.5 i have as a spare ?
GTV6
There are a few different things here.
The oil pressure isn't quite as scary as the funny sounds, to me.
If you could fit a mechanical gauge just to make sure that your oil pressure sender is ok. My GTV6'es have 90psi on startup, and go down to 55 at idle. If you have a bad sender, you could have ok oil pressure, and the gauges are reading low. Also, does the pressure pick up if you rev the motor, or does it just stay at a low pressure no matter what? Ideally, you should see 10psi per 1000 RPM (so >70 psi at 7000 -ha ha). If you really have no pressure once things are warmed up, then either your bearings are no good, or the relief piston in the oil pump is stuck open. Neither is good.
With regard to the noises:
1) I would make sure that everything is ok with your valvetrain:
double check cam timing, lash etc.
2) Consider compression and leakdown-they might be abnormal in the face of some kind of impending engine disaster.
Finally,
if you really want to be sure, just swap in the other motor, and rebuild the GTV6 engine. It is fun (?), and you will learn a lot of neat stuff.
Or, you can simply drive the crap out of it the way it is, and let the problem (if there is one) declare itself.
-Al
The oil pressure isn't quite as scary as the funny sounds, to me.
If you could fit a mechanical gauge just to make sure that your oil pressure sender is ok. My GTV6'es have 90psi on startup, and go down to 55 at idle. If you have a bad sender, you could have ok oil pressure, and the gauges are reading low. Also, does the pressure pick up if you rev the motor, or does it just stay at a low pressure no matter what? Ideally, you should see 10psi per 1000 RPM (so >70 psi at 7000 -ha ha). If you really have no pressure once things are warmed up, then either your bearings are no good, or the relief piston in the oil pump is stuck open. Neither is good.
With regard to the noises:
1) I would make sure that everything is ok with your valvetrain:
double check cam timing, lash etc.
2) Consider compression and leakdown-they might be abnormal in the face of some kind of impending engine disaster.
Finally,
if you really want to be sure, just swap in the other motor, and rebuild the GTV6 engine. It is fun (?), and you will learn a lot of neat stuff.
Or, you can simply drive the crap out of it the way it is, and let the problem (if there is one) declare itself.
-Al
Al Mitchell
Reale Motorsports
#82 E Production
Alfa Romeo GTV6
Reale Motorsports
#82 E Production
Alfa Romeo GTV6