I am helping my buddy with a 2008 Lexus IS 250 6 speed Automatic AWD Sedan with 145000 miles fix his transmission as it won't engage fully into gear and it upshifts hard. Interestingly, there is no codes. Based on those symptoms, I think the cause of these symptoms is a bad throwout bearing and/or bad clutch fork. Am I right?
Is it worth sending it to a transmission shop to get overhauled or is it better to buy a different one already rebuilt?
As @imperator noted in his post, buy a remanufactured transmission and forget about fixing the old one.
Interestingly, there is no codes.
That's not particularly interesting if the vehicle was scanned with a generic OBD2 scanner. Typical consumer-grade scan tools will not read manufacturer-specific automatic transmission codes. (There would not be any codes for manual transmission.)
Based on those symptoms, I think the cause of these symptoms is a bad throwout bearing and/or bad clutch fork.
I thought you said this thing has an automatic transmission? Throwout bearings and clutch forks pertain to manual transmissions.
Has the transmission been properly serviced over the last 17 years and 145,000 miles? If automatic, the fluid and filter should have been changed a few times by now. What is the condition of the fluid? Is it at the proper level?
If it is a manual transmission the gear oil should certainly have been changed by now.
@chucktobias it is an automatic transmission, and he changes the transmission oil and filter every 30k miles with OEM fluid
Then to answer your question, your diagnosis is not correct since there are no clutch forks or a throwout bearing in a conventional automatic transmission.
@chucktobias Ok, I will hook up my fancy scan tool tomorrow and see what it says
@chucktobias I checked the fluid and it is at the proper level. Not burnt or anything.
automatic transmissions don't have a main clutch. The input and output are coupled by a torque converter which works on the principle of hydraulic fluid pressure (hence why fluid changes are so important.. every 50k... from the start). No clutch means no throwout bearing, and no clutch fork. There's not much you can do with automatic transmissions other than change the fluid & filter. For most other problems, the whole unit come out, and at his mileage, there is absolutely no sense in putting the same transmission back in. His symptoms are typical for a transmission that's plumb worn out, and most of the time you won't get any codes for this. So you take the transmission out, and you put an off the shelf re-manufactured one with good warranty back in.
@imperator Ok, thank you! Is it worth sending it to a transmission shop to get overhauled or is it better to buy a different one already rebuilt?
Like I said, off the shelf from a large reputable supplier who has a large inventory of parts and all the proper tools and replaces ALL the wear parts, and dyno tests each transmission. Your tranny should know.