| Author | Message | ||
| Philip Airey (Pma1010)
New member Username: Pma1010 Post Number: 2 Registered: 7-2002 |
Rob Comparative results from a leakdown test performed on my 1977 308 by LFSC earlier this year might be helpful. The results were as follows: 1-6% 2-5% 3-14% ["rings" - their comment] 4-5% 5-4% 6-6% 7-4% 8-6% Drexel (service manager - good guy) opined that many later cars are worse, leave alone. Seems the same advice would apply to you, | ||
| Rob Lay (Rob328gts)
Board Administrator Username: Rob328gts Post Number: 1860 Registered: 12-2000 |
I think it was one hour labor. | ||
| TomD (Tifosi)
Intermediate Member Username: Tifosi Post Number: 1062 Registered: 9-2001 |
how much did they charge you to do this | ||
| Rob Lay (Rob328gts)
Board Administrator Username: Rob328gts Post Number: 1859 Registered: 12-2000 |
He must of been aware of this too, since he retested again after the others and it was still the same. He also said not to do anything, but before I ever did to run it for awhile and then retest. | ||
| Terry Springer (Tspringer)
Junior Member Username: Tspringer Post Number: 140 Registered: 4-2002 |
I dont know about Ferrari engines on this, but on a Porsche flat 6 it is extremely common for leakdown test numbers to be effected by carbon. Tiny piece of carbon can easily be keeping the valve from closing fully and thus a poor leakdown. Often the carbon falls from the sparkplug while its being removed, then fouls with the valve when rotating the engine by hand to TDC or when pressurizing the cylinder so you can test leakdown. I have had 911's engines that showed poor leakdown on a cylinder but when re-testing that cylinder after doing all of the others and turning the engine over a good bit its excellent. If it has good power, this could be the trouble. I think many mechanics wont go through the hassle of retesting bad cylinders to see if carbon was the culprit. I wouldnt worry about it until the power drops off or it begins to smoke badly. | ||
| '75 308 GT4 (Peter)
Intermediate Member Username: Peter Post Number: 1911 Registered: 12-2000 |
Drive and enjoy Rob. To cause 20% leak over a fixed time of a few minutes would be a valve head just bent a hair's worth. Nothing to worry about. Just try not getting stuck in traffic jams that would cause carbon build-up  | ||
| Rob Lay (Rob328gts)
Board Administrator Username: Rob328gts Post Number: 1855 Registered: 12-2000 |
Back at the dyno day a few months ago, my max hp was as healthy as the other two 328's, but mine had a weird sudden 25 horsepower drop about 7.5k RPM. The power loss isn't noticable when driving, but the power curve wasn't normal at high end. It was in for an oil change and fix the A/C, so I also had them do a leak down test. Overall, the car is very healthy, there is one cylinder that is marginal at 20% loss through an intake valve. Here are the overall results... 1- 3% 2- 5% 3- 8% 4- 20% intake 5- 2% 6- 10% intake 7- 7% 8- 4% I just want to hear everyone's input. The car is running really well and is putting out good power, so even with those 2 cylinders that could be improved upon, I don't think it's worth taking the heads off to fix. I was told it's probably carbon build up. Floating a valve or a broken valve spring would show more of a loss than 20%. It could be just a little break in the valve spring though. Any thoughts or advice would be appreciated. I think I will rebuild the engine in 3-4 years for the fun of it and I think it's healthy enough until then. |