latest 4.1 repairs

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 2 of 2
HT4100 4.1, 4.5, 4.9 Discussion, latest 4.1 repairs in Cadillac Engine Discussion; Okay, I had a list of small problems with my 4.1 which was motivating me into the 4.9 swap, but ...
  1. #1
    ehall's Avatar
    ehall is offline Cadillac Owners Connoisseur
    Automobile(s): 1985 Sedan DeVille
    Join Date
    Aug 2007
    Southern Maryland

    latest 4.1 repairs

    Okay, I had a list of small problems with my 4.1 which was motivating me into the 4.9 swap, but I figured I would see if the easy fix worked and that would take pressure off having to do the 4.9 under duress.

    Problems were: periodic lean error (E44) after warmup, uneven acceleration after warmup (but not cold that was fixed separately), vacuum pump getting louder as temperature increased, and oil analysis showed higher than normal levels of dirt and coolant. I also had a long-term problem with random oil consumption, and low compression. The failure that would explain all of this was a leaking intake gasket, but I also thought there could be some other problems, so I had a mechanic run some tests.

    He tried the easy and obvious thing first which was to monitor the O2 sensor, and sure enough it showed good, but it was also showing the temperature bouncing around a bunch, even to the point where the car was dropping in and out of closed loop on the highway.

    On to the serious tests. A leakdown test showed that one cylinder has minor exhaust valve leak, while three cylinders have minor blowby issues, but nothing major. There was no coolant leak. The exhaust system also tested fine. The engine core is solid, which is good news and kind of surprising for HT4100 with 138k miles.

    So given the history of intake gaskets, I had the mechanic install a new Felpro, and also gave him new valve cover gaskets. After he got the lid off he said that the existing one actually looked fine with no visible damage. However I am hoping that some micro leaks were fixed anyway, and maybe the bolts just needed a good torquing. One of the engine shops I talked to said that the manifold probably needed to be resurfaced, but that was after the fix.

    Anyways... he buttoned everything back up, reran some tests and ... O2 still showing wild temperature readings. Shit. So he started doing some more tests, and traced the leak down to the butterfly valve connector rod which had excess play from a crack. I picked up a replacement TB from a yard for $60 (remans are $200-400 btw), and it took care of the problem.

    I took it out for a long drive this morning and the problems with lean error and uneven acceleration are gone. I will not know if the consumption problem is fixed for a while yet. I assume the high dirt content is resolved, and am guessing that the high coolant levels were from spillage and blow-off getting sucked into the TB.

    I still have a couple of small problems--uneven bubbly at highway cruising, and wanting to stall at red lights sometimes. However I think those will be fixed with replacement TPS and ISC, which are both old. I also need to have the timing bumped up again. Otherwise I am told (again) that my engine has +60k miles left on her...

    Now to build the 4.9...

  2. Remove Advertisements

  3. #2
    behind-bars is offline Cadillac Owners Connoisseur
    Automobile(s): 93 Sedan Deville 4.9L
    Join Date
    Sep 2005

    Re: latest 4.1 repairs

    TPS is a fun one to have fail, Had I not have known mine was broken I would have had a heart-attack when I couldnt accelerate above 20 mph with the engine revving and the pedal to the metal. lol Would have definately thought transmission, but a new $30 TPS was all it needed.

    Glad you got some of your issues fixed

  4. Remove Advertisements
    Cadillac Forums

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

What Cadillac(s) do you own? (Or type NONE)

Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts