News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

Throttle Body

Started by 80redcoupe, May 15, 2022, 10:03:59 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

80redcoupe

Team,

I am in a bad way..... My mechanic has caused a problem that he can not solve. In attempting to get my 81 running right he was trying to replace the TPS. Well... the screws broke in Throttle Body. He removed it and tried drilling and tapping. Unfortunately the holes got HUGE. Tried installing helicoil and can't get TPS to adjust properly due to holes being too big.

Does anyone have a throttle body they would be willing to part with? I'm dead in the water without one.

Not sure if any other year will work. My car is a 1981 with the 368 and 468 system.

PLEASE message me if you can assist.

Thank you
R Clerie

The Tassie Devil(le)

Have him try some product like JB Weld.   Fill the hole, then tap it out correctly, and replace the screw/fastening.

I have used that stuff in a Motor Bike Sump to correct a cracked case, and it worked perfectly.

There will be other thread repairing material that will consist of a two-part epoxy to fix such dilemmas.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

TJ Hopland

Can you post some pics of the damage?  Maybe someone here will have some ideas on how to repair it?


I would guess that the part numbers are different for different years but how different they are is a good question.

Just thinking out loud from memory not actually doing any research.....

I would guess that an 80 DEFI cad would be very similar if not the same.   Eldo/Seville vs RWD should not make any difference.

The 82+ 4100 Cads may be similar overall but I would guess a smaller bore so far from ideal.  By 91 with the 4.9 they went to multiport injection.  Maybe you could try and find and check the bore size on a 88-89 4.5 cad? Maybe it was bigger than the 4.1 was?  90 4.5 was multiport.   Maybe they were all the same bore size?   The bore size isn't as important as it was for carbs so maybe there was only one size and they just put different injectors on depending on engine size?

By the time the TBI systems made it to the trucks (1987) there were several changes so I don't think a truck one would be even close.   Among the changes the truck ones used a IAC rather than the external throttle stepper.

There were other GM's that used the TBI's on the V8 early on but I'm not sure if they had the larger bore sizes and I'm not sure if they used the internal or external idle setup.  I don't think they were super common or made for many years.  I know many of the 81-85 V8 cars still had carbs.  If there were any they would have been an odd option or CA option on maybe a Corvette or Firebird/Camaro.   I think the 305/5.0 and 350/5.7 throttle bodies were the same bore size, just had different injectors.  454/7.4 was a larger bore but were the later IAC design by the time they came out in 89 I think.     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

smokuspollutus

Unfortunately, the '81 throttle body is a one year only part. I agree with Bruce, fill the holes with JB weld, drill them back out, and tap. It will be a challenge to get right, as you want the holes to be as close to the original position as possible to keep the linearity of the TPS vs actuator the same. But it is doable.

80redcoupe

Thank you TEAM!

I like the JB WELD idea! Never thought of that.

I will get to work on this.

THANK YOU ALL!
R Clerie

TJ Hopland

How about making them into studs?   At least that way you don't have the extra forces and stress of tapping and threading a screw in.   With a stud if you can basically glue it in it stands a decent chance of holding.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

TJ Hopland

Quote from: smokuspollutus on May 16, 2022, 12:58:47 PMUnfortunately, the '81 throttle body is a one year only part.

Are you looking at a part number for the complete assembly?  Or a breakdown that shows individual parts including the main casting?  I could easily see the assembly being different but that could be something easily transferable like a connector or bracket.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

81 BENY Biarritz

Good morning,  I have a couple of 81's with the 368 in them.  I regularly keep an eye open for various "unique" replacement parts for them and have found a number of parts cars in on line searches over the past two or three years.   I did find one locally that I pulled the throttle body off myself only to find out that there were two different versions used that year!   The one that I pulled came from an early production number car and both of mine are late year cars.    I haven't figured out what the difference is yet but it is something that you should be aware of if you do come across one for sale on E-bay or the like.   I also know of a car that I think is still in a U-pull yard that probably still has the TB on it and might be able to recommend a parts puller to you.   If you want to PM me I can send you the contact info for him.   On this car the throttle body attaching screws are installed in a way that prevents tampering with them.  To remove them you need to drill two holes that effectively shear off the very end of the screw so that you can back them out (easily).   Your mechanic probably didn't know about this procedure and sheared the heads of the screws instead.  It is covered in the 1981 Cadillac Service Manual (as well as the setup procedure for the new TPS) so if you don't have a copy yet I would strongly recommend getting one from E-bay.   They are cheap and well worth the money.   Hope this helps and feel free to contact me directly for more info.  Dave 

smokuspollutus

Quote from: TJ Hopland on May 16, 2022, 11:18:37 PM
Are you looking at a part number for the complete assembly?  Or a breakdown that shows individual parts including the main casting?  I could easily see the assembly being different but that could be something easily transferable like a connector or bracket.

The '81 has a large bore as well as the connections for the vacuum pump. The 80 shares the bore and arm but lacks the vacuum hookups. The 82-85 have a smaller bore and different throttle arm. The transverse ones are different.

TJ Hopland

Did the DEFI cars with the THM400 still use a similar kickdown switch as the earlier cars did?   Or did the computer send the signal to the trans when needed?   The few 368's I worked on were in E's so they didn't have an electric kickdown, they used a cable which I suppose could make at least the arms different on FWD vs RWD. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

80redcoupe

Team,

I decided to just find another TB. I found one on Rock auto..... NOT CHEAP....

But, I didn't feel right "trying" to fix it. Here is to hoping it's the right one.

R Clerie

81 BENY Biarritz

If you want any pictures of the early version of the 81 T/B let me know and I will post a few so that you can compare them before you install it to make sure it is the right one.   You don't want to try and return something that is used and didn't work, as well as pay for the mechanics time if you find out it isn't the correct one.   I believe that there are specific date and manufacturing codes that are cast into the body that should be able to confirm that you have the correct one (providing it is a rebuild).   Unfortunately Rock Auto isn't always correct with their P/N info.  Dave 

80redcoupe

Beny,

If you wouldn't mind posting the pics.... i would greatly appreciate it! :)
R Clerie

81 BENY Biarritz

Here are some scans from the original Cadillac parts manual (4 pages).   Looks like the Fleetwood throttle body has a different P/N than the one used on the Eldo and Seville (my cars) and didn't have a mid model year change as I had mentioned.   The spare T/B that I have is from an early production # Eldo so it probably will be slightly different than what is on your car.  Interesting to see on Rock Auto that they don't show the T/B to be available for the Eldo/Seville.   I will send a picture from the silver 1981 Cadillac Service Information book showing the T/B casting identification #s when I have more time tonight.   If you don't have this manual already,  I highly recommend you pick one up from E-bay.   I seen them regularly for about $20 and up plus shipping.   They are an invaluable resource.  It shows how the screws for the throttle position sensor are factory welded in place and that you need to drill the tip of the screw off to get them to release and be able to replace the TPS.  I think your mechanic didn't know about this and probably put you in the position you are in now, so if that is the case maybe you should ask him for a discount on the remainder of the work as you are now out the cost for a new T/B.
Once you get it installed and if you want any of the sensor diagnostics readings to compare to what yours is doing let me know.  I am always looking to help out anyone else with info on the 368, V864 as I learn more along the way also.   Dave

80redcoupe

Dave,

Thank you!

The mechanic has agreed to be gentle. Very good guy... Apologized up and down. Even offered to pay for the TB. The way I figure... It's a mistake. Hopefully somewhere down the line, I will get some good karma in return.

I wanted to ask the team here.... I looked at the procedure for setting ISC. Can it be pushed back in out of the car? I have a new one and want to set it back in before I give it to the mechanic to install. He is an older guy and don't want to risk a mistake again. I did order the shop manual on Ebay.
R Clerie

81 BENY Biarritz

Good morning,  this is the picture that I mentioned from the manual.   Hopefully your P/N matches up to the original T/B.
As for the ISC motor you will find lots of detail on how it works and how to test and set it in the silver Service Manual.   I haven't ever worked on mine so can't advise on resetting it without it being installed on the car but I would wait until you have the manual and then figure it out from there.  Read up also on the sensor readings display function that is available in the diagnostics mode and if you have any questions about any of your values let me know and I can send you a short video of mine with the car running.   Hope it helps and good luck.   Dave 

80redcoupe

Team,

I wanted to provide an update on the Rock Auto TB. It is an EXACT MATCH! It comes complete with injectors and TPS installed. It looks like a very respectable part. I will be sure to keep everyone updated as we navigate this repair.

I do have a NEW situation to share.....

Now when the key is turned off, the ISC continues to ratchet.... Quite odd that this happens with the key off. Only solution was to disconnect battery. I am now hoping that the ECU is not fried.....

Can it get any more interesting????
R Clerie

81 BENY Biarritz

Great to hear that the T/B turned out to be the correct one and that it came with all the extra replaceable parts already installed.  Did it also come with the ISC motor installed and maybe it is defective if that is the one that is acting up?   Does it stop once you remove the battery power and then reconnect it or does it continue to ratchet again?  In the silver manual the electrical diagram for the control circuit will be shown and also a troubleshooting page for the error code that should be generated so maybe that will give you a clue as to what to try next.   
I sent you a PM on Friday to a link to another site that you might be able to do a search to see if anyone else has had a similar issue. Just click on My Messages on the header at the top of this page to find it.  If nothing else it is interesting reading and I am sure you will find some useful info somewhere in the thread that is shown in the link.  Dave