THM200 Metric transmission

Status
Not open for further replies.

MontyCarlo85262

Not-quite-so-new-guy
Aug 1, 2011
11
0
1
Hello Everyone, Im new to this forum. I bought a 1985 Monte Carlo last year in beautiful shape. It had low miles on it and wasnt driven much. When I bought it it had a bad miss. Replaced plugs,wires,cap,rotor,Map sensor.TPS.O2 sensor and all fluids and filters. I still had the miss. I took it to a GM dealer and was told that the torque converter was bad. It had engine shutter.So this summer I replaced it. Still having problems. The Miss is there and when you drive it. It starts out in first and before the RPM's come up the trans shifts thru the gears and the RPM's have to build up to get it going again.Id like to keep the car all orginal. Was hoping someone out there may have a sulution to my problem.
 

Dragonist

Master Mechanic
Dec 3, 2010
424
0
16
Dallas, Tx
check your transmission fuild...thats where i would start first...than check your timing
 

MontyCarlo85262

Not-quite-so-new-guy
Aug 1, 2011
11
0
1
Dragonist said:
check your transmission fuild...thats where i would start first...than check your timing

Did all that.. New fluid and No one has messed with the timimg. Someone told me it may be the govner on the transmission maybe plugged up. Its still doing it even with the new torque converter.
 

G-Body_Vet

Comic Book Super Hero
Oct 15, 2010
2,937
81
48
I hate to be the bearer of bad news, but the best remedy for a TH200 is a different transmission. A TH350 is a bolt in deal and much stronger if you just want a 3 speed replacement. It's not even worth keeping for the sake of originality.

If it's a low mileage car, maybe it is just something repairable right now. No offense to you but it really is just one turd of a transmission.
 

Longroof79

Rocket Powered Basset Hound
G-Body of the Month
Oct 14, 2008
12,156
9,762
113
Gainesville, Fl
G-body Vet is correct. Those trannys are boat anchors. You may want to look into replacing it with either a TH 350 or a 200-4R which will be pricier.
 

megaladon6

Comic Book Super Hero
May 29, 2006
4,006
15
0
Danbury, CT
first you need to make sure it's a th200 and not a 200-4r. is it a 4 speed or a 3 speed?
pull your spark plugs and check their condition. if possible, post pics of each plug with it's cylinder number.
honestly, i doubt it's the trans causing the miss. more likely is an EGR or a cylinder problem.
also, take a look at the harmonic balancer and the timing mark. sometimes the rubber outer ring slips making it impossible to set the timing correctly. one way to confirm is to mark where the timing is now, then turn the distributor advanced/retarded and see if anything improves.
 

Longroof79

Rocket Powered Basset Hound
G-Body of the Month
Oct 14, 2008
12,156
9,762
113
Gainesville, Fl
I didn't even pay attention to the year. It most likely is a 200-4R. The 200-4R also indicates "metric" on the pan. As for diagnosing the miss, Megaladon is on the money.
 

MontyCarlo85262

Not-quite-so-new-guy
Aug 1, 2011
11
0
1
Wow, Thanks for all the imput Guys. I talked with a buddy of mine and we decided to switch out the Metric thm200 for a 350 turbo. I think it will be the best choice. Also It is a 3 speed trans. As far as timing I never messed with it to see if there was any diffeance. The car runs good untill it warms up and then the miss comes in. When its at an Idle it misses put in gear and go for a ride and the trans acts up. Ive changed everything I can think of and still the same problem. Its really driving me crazy. The car only has 30,000 miles on it and I was told it just needs driven but it seems to get worse the more I drive it.It doesnt smoke or use oil . Trans and oil are all new . Plugs ,wires,cap, rotor have less then 300 miles on them. EGR valve is working good not plugged. All the plugs are clean. Ive even sprayed either around the intake to see if its leaking and cant find anything. Ive gone over this thing for 3 months and cant find anything.
 

bill

Royal Smart Person
Jul 11, 2008
2,332
11
38
southside va/lake gaston
Just curious....what engine is in your car? If its a 3.8L v-6, my guess would be a carb issue. Also, if it runs fine till it gets hot, then you may have a choke problem or a intake manifold leak and/or a vacuum problem. When you say the trans acts up, exactly what do you mean>? shifts funny? slips? jumps out of gear? Make sure your vacuum hoses are good and are not too soft where they turn, they could collapse and cause issues. Check the pcv valve and clean or replace it.
 

MontyCarlo85262

Not-quite-so-new-guy
Aug 1, 2011
11
0
1
bill said:
Just curious....what engine is in your car? If its a 3.8L v-6, my guess would be a carb issue. Also, if it runs fine till it gets hot, then you may have a choke problem or a intake manifold leak and/or a vacuum problem. When you say the trans acts up, exactly what do you mean>? shifts funny? slips? jumps out of gear? Make sure your vacuum hoses are good and are not too soft where they turn, they could collapse and cause issues. Check the pcv valve and clean or replace it.
No its a 262 V6 with a TBI I changed the TPS because I was told that was an issue. Also changed the O2 sensor. Checked all the vacuum hoses also. It almost acts like it has a cam in it like someone put a bigger cam in it . You know how and engine lobes with a cam. The trans shifts funny. when you slow down to make a turn and get back into the throttle it drops to first and then before you get the RPM's up it chifts all the way to 3rd and the engine chuggs like a standard trans if you skip a gear. PCV is new. all the vacuum lines are plastic with rubber connections.
 
Status
Not open for further replies.

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor