"wet" throttle position sensor

#1

In my continuing quest to clean up and dry up my engine, I noticed that my TPS is covered in some fluid (might be oil or PS fluid or brake fluid - didn’t smell like anything) but the items around it are relatively clean. Where might this fluid be coming from? I noticed that the inside of the intake boot (the rubber part attached to the manifold) has a bit of fluid (oil?) in it, and the old air filter had an oily looking strip in one section.
thanks,
bruce

Post edited by: leggwork, at: 2006/05/04 11:26

#2

just to follow up on what the problem is for the archives - this is caused by the crankcase being pressurized (blowby past the rings) forcing oil up the crankcase ventilation tube where it is supposed to feed into the throttle body area. The intent is to feed the oil into the intake so it gets burned up. In my car it was also dripping down the intake tube onto the air filter and seeping around the TPS. This implies a bottom end rebuild - I’m currently waiting to see if the problem still persists after I gave it an "italian tuneup" - a good long high speed run (LA to Denver when I picked it up). The car passed emissions under the fast-pass criteria so it’s not spewing hydrocarbons into the exhaust at least.
bruce

#3

Bruce, for engines that are out of chassis or prospective purchase engines: buy a compression tester from BMP or others and check each cylinder’s compression.160psi is a good number to hope for. For better analysis do a cylinder leak down test. Again BMP has the part to do the test. For a car that already runs, spend $100 at the dyno for the definitive test of performance.Above 140hp should have you in the ballpark. I look forward to some head-to-head dyno numbers at this week’s Nationals as my engine is strong on "paper", but is like in performance on the track. As a group we’ll be able to report back to you on Monday…Then there is the high altitude factor, why can’t comparisons be simple? Regards, Robert Patton

#4

FYI, it’s hard to do a good leakdown test.

Also, a motor that has been sitting for awhile generally won’t make as good of compression numbers as one that has been run recently. If you get a decent number compared to other motors of that family you are probably fine if they are all within a few percent of each other.

For those selling a car you can pour a teaspoon of oil down each cly before meeting the prospective buyer. Run the car till it quits smoking and do a compression test right when the buyer arrives. You’ll get a slightly better number i’ve found. Restore and other additives are available that make a similar result on a worn out motor.

PS I didn’t tell you that trick and I’ve never used it before when selling a used car i’ve trashed. :whistle: