I have a 1988 XX Generation 3 Honda Prelude. It has an automatic gearbox that does not select 1st correctly. The problem occurs when the automatic is hot or under load. It acts like a slipping clutch in a manual shift box. I have changed the fluid and used the Honda ATF additive. The problem decreases when new fluid is installed. All other gears select correctly. I have had this problem for about 20,000km and it has not gotten any worse. The vehicle can be driven satisfactorily by manually selecting 2nd and thus avoiding the 1st gear problem. I need to know the possible source of the problem and the solution. Alternatively can the problem can be bypassed by using a synthetic ATF with a wider operating temperature range or by installing a fluid cooling devise.

I flushed (or pumped out) the box when I changed the fluid. The problem remained and it only occurs when in DRIVE and when the box wants to automatically select 1st. I am only manually selecting gears when stopped so I can get the vehicle off the line. I then change up to drive when the car is in motion. There is no position on the selector to engage 1st manually. The lowest gear that can be selected manually is 2nd.

I have had a mechanic take it for a drive around the block and he told me that he would fix the problem for more than the price of a replacement box. He said that it was a seal like a rubber O-ring that needs replacing. I find it difficult to justify that kind of money to fix a small intermittent problem. I am looking for alternatives and a better idea of what the problem actually is.