Living with a THM200-4R ? Happy, happy, joy, joy, I'm just about to pull the trigger on a 1989 Buick Lesabre Estate wagon. (77K miles) Now for the sticky parts: I'm told it has the Old's 307 5.0 L and THM200-R4 overdrive trans. (I have yet to fully decode the VIN, but the engine code is "Y" and the shift indicator is PRN(D)DL, in a gage like circle in the dash, between the spedo and gas gage. Questions: How tough is the THM200-R4 ? When should I select the Overdrive position? (around town, normal driving or open road/hiway only?) Can I tow in OD? Can I tow a light (1500Lbs) trailer (class IV hitch) without undue strain or problems. (will it need extra cooling or larger fluid capacity?) My purpose for this rig is primarily medium range (200-1200 mile) cruising, pulling a small travel trailer. (what towing MPG?) Good choice or will it need modifications? Tell me everything I need to know... Thanks, Paul
The 200-4R is not stout in stock form. Buick GN's used them, but were upgraded. They can be modified to take the abuse, but the foundation has its limitations. Check with Buick forums for advice. RealOldsPower.com had recent thread on mods to survive regular drag runs.
If you have the Olds engine, it's a 307, not a 305 - which is the size of the Chevy engine that some of the box wagons had. You have a maximum tow rating of 3000# I believe. Check your manual. You can leave the trans in overdrive all the time in normal driving. You're probably OK in overdrive with a small trailer of 1,500# or so..... Probably a good idea to put a trans cooler on if you tow regularly.
The 200 4R's are fine for a stock vehicle. No worries. The early ones could blow out front seals but that was fixed in I think 86. We are running one behind an Olds 350 with add ons and have no problems. Much more power than a stock 307.
I've got a 200 overdrive in my 86 Monte Carlo SS. I've never towed with it, but I'm sure it would pull your trailer. I'll bet I've had that much weight IN it. I had it rebuilt at 210,000 miles, because it started to leak a little. I figured if I had to pull it to reseal it, I might as well have it rebuilt. The shop that builds overdrives for me told me it didn't seem bad in there, couldn't believe it had 210,000 miles on it. It now has 246,000. My car is powered by the 305HO (WOW) which I think was rated at 180 or 190 hp. Obviously, I didn't buy it to be a performance car with that engine, but it has proven to VERY dependable. It has never let me down. You should be fine with that low mileage wagon.
Another. I have a 200 4R and 305 SBC in our 55 Chevy wagon. Never towed or hauled anything but I see no problems with these transmissions. As for towing in overdrive they told me at the Dodge dealership when I bought my hemi Dodge with OD that as long as it does not keep shifting up and down it's fine to tow light trailers. I pulled a 23' Terry RV for years even in some small mountains. I'm sure this is true with any overdrive. When in doubt kick it out of OD. Always add an external tranny cooler for any towing. Bypass the radiator. Cheap insurance. I don't know why 2004R's got a bad name. More 700R4's seem to go bad.
I tow my car trailer with cars and trucks on it all the time with my 01 Tahoe. I'm always in Overdrive on the freeway..........with the cruise control on. If it starts ownshifting, or lugging, I turn the cruise control off. 219,000 miles, never a problem.
Wow, thanks for all the quick reply's. The plan is to add a trans cooler and a deep sump, cast aluminum, tranny pan, just in case. What can I do to get some of the power back, that the smog stuff takes away? (short of stuffing in a 500 cuin Caddy engine, lol.) How much "computer junk" lives in this beast, and how much of it can be exorcised? ( I am a great believer in the KISS principle) Thanks, in advance, for the schooling. Paul
As for how to get more power back, well I would go with 500 caddy engine. I have the same everything in my 87 Buick but propane powered and you are not going to gain much if any real noticeable 'UMPH" no matter what you do to the 307. To dump $ into it for upgrades you would be better off finding a rebuildable 350 Buick. Myself I am a skeptic, if you live on flat ground I would say your 307 should do OK towing a trailer on flat ground yet even with trany upgrades I really don't think you will like the over all power ( more like the lack of...) if you will drive longer steep grades.
We live basically in the same area. Not many mountains in Florida, except Space Mountain. We had a Chevy van with either a 305 or 307 and traveled between Florida and Illinois often pulling our 23' RV. Lots of long grades on I-65. We went to the Smokeys often and many other fairly steep "hills." I'd say with a tranny cooler you should do okay. Why not just enjoy the wagon with an added tranny cooler and hitch and see how it performs. Then you can decide if you want to spend a lot of time and money going big block. Remember old cars pulled old trailers when you and I were little boys.
The 307 Olds motor and 200-4R was the only powertrain combo available in 1989. The trans is marginal in stock form, depending on how you drive. I've blown up two of them behind stock VIN Y 307s with a pavement-ripping 140 HP (on a good day). I never towed, but I do have a heavy foot. Properly built the 200-4R is a great trans. I'd recommend CKPerformance as a source for parts and info. And no, you cannot tow in O.D. There isn't much you can do with the 307, especially the roller cam versions used from 1985-1990, as these have the peanut-port 7A heads and matching intake and exhaust. The best you can do is to make sure the CCC system is properly tuned and adjusted. VERY FEW people know how to do this, which is why the first reaction is to dump the CCC system and use a non-computer carb and distributor. Once adjusted properly (you MUST follow the procedure in the Chassis Service Manual EXACTLY), they run great. The CCC system in my wife's 1985 Delta 88 performs flawlessly. Upgrade options are any GM engine, though Olds engines are a bolt-in. Any Olds 350 or 403 is a direct replacement for the 307. An Olds 455 requires only slightly more work in the form of accessory bracket mods and exhaust changes. Of course, any of these will require an upgraded 200-4R if you want to get past the end of the driveway before the trans blows up.
Those are the same things I hear about the 700R4. In all the years I've driven, sometimes abusing transmissions, I've had one go bad. It was already questionable when I bought the old Buick with Dynaflow. Had it rebuilt at Buick dealership and no further problems. Worst tranny I had was in my first car, 49 Dodge with Fluid drive. Actually had no problems with it but as a teenager it woudn't peel out! All of the negative talk about the 307 and yet millions were on the road trouble free. True they never were a powerhouse. After all, this wagon is still moving on it's own or you wouldn't buy it. As I wrote, drive the wagon and see how it feels. If it keeps downshifting while pulling a trailer just kick the OD off.
