23racer
08-15-2005, 11:45 AM
Really odd thing happened at Mosport this past weekend, trying to narrow down the problem before ripping the whole thing apart.
Some background. I am running a stock 86-88 6port in our Touring GT Championship, sorta a poor mans Speed GT. I am running an RB Baffle plate, the 80 psi pressure regulator, a 2 quart Accusump, new stock cooler and a remote filter.
The scenario. Out for the first time with this motor. Bought it from a kid as a runner, saw it running in the car before I removed it. Compression/ oil pressure were good. Added the above pieces to the motor and installed it all into my car. Fired it up and all pressures were good. 60 lbs oil pressure at 1500 rpm when cold, up to about 80 psi at 5000 rpm. Car starts first ignition spark. Looked good.
Went to Mosport and ran it in Practice. Car ran for 10 mins full out, good power, oil temps about 180 - 200, pressures about 80 psi all through the session. Checked the car over after the session, no leaks, no oil in water, level the same and about 3 teaspoons of oil in the puke tank (less than normal).
Ran it in the first 20 minute race, it was spitting rain, so didn't get to go too hard but got down to within 12 seconds of my best dry time. Power good, pressures normal (80 psi max idle at 30 psi) and oil temp maxed out at 210. Checked the car over and had about half a cup in the puke tank. Another competitor came up to me and told me that the car was puffing blue when shifting. Oil level was about the same as when we started, down 1/4 quart. Looked at the car and found that 1 of the 2 crankcase vent tubes was capped (we normally run both vented to atmosphere) and felt that not having enough ventilation was causing a pressure buildup and less than optimal oil control rings weren't controlling the oil well. We were cool and as long as we added additional venting before the next race weekend and didn't run the oil out we would be fine.
Ran the 40 minute race. Didn't get a chance to open the Accusump on the mock grid. Again it was spitting rain. Couldn't push too hard. Oil pressure remained as per previous 80 max, 30 idle, oil temps were in the 180 to 190 range, water about 170. At the 30 minute mark the oil temps started to slowly drop, down to about 170. After a couple of laps the oil pressure started to drop. Up the back straight at about half throttle it dropped from 80 down to about 40, then 30 at 4000 rpm. Then when I slowed for the pits idle pressure was about 15 - 20 psi but dropping without me revving it up. Oil temps were still at about 160 degrees, water at 160 degrees as well. Crew chief opened the Accusump and pressure went up to about 40 psi. I saw the last lap board and went out for 1 slooow lap. Maintained my position in the race as I was substantially ahead of the next car, but by the time I came across the start finish I had to keep it at about 4000 rpm to keep the pressure above 20 lbs, but the temps were at 150 -155 degrees. Pulled into the pits, shut off the car. Checked the oil level and it was slightly above full (forgot to shut off the accusump), the oil was barely colored, no metallic bits, no burn't smell, etc.... We had about 1/2 a quart in the puke tank (again normal). Let the engine cool off for about an hour and fired it up to put it on the trailer. No weird noises, started very quick, no smoke puffs but oil pressure max about 25 psi, idle about 10 psi but erratic (too chicken to let it idle for too long to get a steady rate).
Don't think I wiped out the bearings as temps did not rise a bit and the oil looks almost new. What is the pump failure mode or a pressure regulator being stuck open with some slag failure mode. Could it be the thermal pellet in the eccentric shaft?
Oh guru's with more rotary experience than I please give me your opinions and trouble shooting tips.
Thanks a bunch in advance.
Some background. I am running a stock 86-88 6port in our Touring GT Championship, sorta a poor mans Speed GT. I am running an RB Baffle plate, the 80 psi pressure regulator, a 2 quart Accusump, new stock cooler and a remote filter.
The scenario. Out for the first time with this motor. Bought it from a kid as a runner, saw it running in the car before I removed it. Compression/ oil pressure were good. Added the above pieces to the motor and installed it all into my car. Fired it up and all pressures were good. 60 lbs oil pressure at 1500 rpm when cold, up to about 80 psi at 5000 rpm. Car starts first ignition spark. Looked good.
Went to Mosport and ran it in Practice. Car ran for 10 mins full out, good power, oil temps about 180 - 200, pressures about 80 psi all through the session. Checked the car over after the session, no leaks, no oil in water, level the same and about 3 teaspoons of oil in the puke tank (less than normal).
Ran it in the first 20 minute race, it was spitting rain, so didn't get to go too hard but got down to within 12 seconds of my best dry time. Power good, pressures normal (80 psi max idle at 30 psi) and oil temp maxed out at 210. Checked the car over and had about half a cup in the puke tank. Another competitor came up to me and told me that the car was puffing blue when shifting. Oil level was about the same as when we started, down 1/4 quart. Looked at the car and found that 1 of the 2 crankcase vent tubes was capped (we normally run both vented to atmosphere) and felt that not having enough ventilation was causing a pressure buildup and less than optimal oil control rings weren't controlling the oil well. We were cool and as long as we added additional venting before the next race weekend and didn't run the oil out we would be fine.
Ran the 40 minute race. Didn't get a chance to open the Accusump on the mock grid. Again it was spitting rain. Couldn't push too hard. Oil pressure remained as per previous 80 max, 30 idle, oil temps were in the 180 to 190 range, water about 170. At the 30 minute mark the oil temps started to slowly drop, down to about 170. After a couple of laps the oil pressure started to drop. Up the back straight at about half throttle it dropped from 80 down to about 40, then 30 at 4000 rpm. Then when I slowed for the pits idle pressure was about 15 - 20 psi but dropping without me revving it up. Oil temps were still at about 160 degrees, water at 160 degrees as well. Crew chief opened the Accusump and pressure went up to about 40 psi. I saw the last lap board and went out for 1 slooow lap. Maintained my position in the race as I was substantially ahead of the next car, but by the time I came across the start finish I had to keep it at about 4000 rpm to keep the pressure above 20 lbs, but the temps were at 150 -155 degrees. Pulled into the pits, shut off the car. Checked the oil level and it was slightly above full (forgot to shut off the accusump), the oil was barely colored, no metallic bits, no burn't smell, etc.... We had about 1/2 a quart in the puke tank (again normal). Let the engine cool off for about an hour and fired it up to put it on the trailer. No weird noises, started very quick, no smoke puffs but oil pressure max about 25 psi, idle about 10 psi but erratic (too chicken to let it idle for too long to get a steady rate).
Don't think I wiped out the bearings as temps did not rise a bit and the oil looks almost new. What is the pump failure mode or a pressure regulator being stuck open with some slag failure mode. Could it be the thermal pellet in the eccentric shaft?
Oh guru's with more rotary experience than I please give me your opinions and trouble shooting tips.
Thanks a bunch in advance.