At 12:02 pm 3/14/97 PST8, you wrote:
> I am having an problem with low oil pressure on my Mark 1. When I
> start up the car after it has cooled off, I have a healthy pressure of
> 65 at idle. This remains fairly constant for the first 10 minutes of
> driving and then the oil pressure drops rapidly until I have about 25
> psi at idle and 45 at 3000 rpm. This phenomenon seems to occur whether
> the engine temp gets up to 205 degrees or on cool nights when it stays
> down around 170. It seems to be more time dependent rather than temp
> dependent. The engine is relatively new (2500 miles) and tight, the
> oil pressure line is new and doesn't leak, new high volume melling oil
> pump, and I am running 20w-50 Castrol. My next step is to try a
> different pressure gauge and also get an oil temp reading, but was
> wondering if there is anything Tiger unique that might be going on
> here.(ie early signs of gauge failure, gauge susceptibility to hot oil
> temp. or???)
> Any help would be appreciated.
> As always, all is meant in fun and jest as there are too many serious
> issues to deal with in life, without making cars one of them.
> Jay Peterson
Jay,
I has a similar problem with a new engine (15K miles)after I wiped
a lobe off of a Ford Motor Sports Cam. The steel particles apparently
scored the bearings. I changed out the rod and main bearings, but that
didn't help much. I believe that the cam bearings may have been damaged.
Did you or your rebuilder replace the cam bearings correctly?. Did you
or your rebuilder check the rod and main bearings clearance with plasticgague?
You should drop the pan ( easy to do on a Tiger) and check the bearings
with plasticgague. Also check that the oil pump is sealed to the block.
(thin gasket, aviation cement and properly torked bolts). This would be
an excellent time to change the rod bolts for new or better yet new
ARP or equivilent bolts. You will not be able to check the cam
bearings except by removing the cam ( major work).
I assume that the "time dependent" case on cool nights is due to
hot oil. Is your oil cooler connected?
There is a valve in my Tiger II oil cooler that opens when oil gets
hot and allows oil to flow through the cooler. Maby if you have a
Tiger oil cooler, the opening of the valve after 10 minutes of running
is the cause of the oil pressure drop. I am not sure about the amount
of restriction (or extra flow) due to the cooler.
Any one on the Tiger list have an opinion on oil cooler flow?
If you solve the problem let me know because I have a Caprii
V6 in an Alpine that has a worse problem with oil pressure and I
have been unable to solve it. 18lb idle, 30 lb or less when hot.
Jim Barrett Tiger II and others.
|