HT 4100: Avoid at all costs????? Help!
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 11 of 11
HT4100 4.1, 4.5, 4.9 Discussion, HT 4100: Avoid at all costs????? Help! in Cadillac Engine Technical Discussion; I am interested in a very clean 80's model Cadillac, around 60K miles, well serviced and pampered .... but with ...
  1. #1
    caddymark is offline Cadillac Owners Fanatic
    Join Date
    Aug 2006
    Posts
    171

    HT 4100: Avoid at all costs????? Help!

    I am interested in a very clean 80's model Cadillac, around 60K miles, well serviced and pampered .... but with the HT 4100 4.1 engine. I have heard so many negatives about this engine. Should I avoid the 4.1 engine? There are other Cadillacs (and other makes) that I like from the 80's/early 90's that do not have the 4.1. What would you recommend? Avoid the 4.1? Thanks!

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    noahsdad's Avatar
    noahsdad is offline Cadillac Owners Connoisseur
    Automobile(s): '87 SDV
    Join Date
    Jun 2005
    Location
    Michigan
    Age
    55
    Posts
    1,296

    Re: HT 4100: Avoid at all costs????? Help!

    Depends a lot on what year. The early RWD cars had the most trouble, because the engine was not designed for them. If it's an '82 or '83 full size RWD, I would be cautious but not run from it. Check the valve covers. If they're chrome or black with aluminum fins, it's the original engine (not a deal killer, but not the best news). If they're a plain black cover, it's been replaced with an updated engine (very good). If it's an '85 to '87 FWD car, there is much less to worry about.

    On the car you are looking at, check for any sign of oil/coolant contamination: i.e. a milkshake color to the oil on the dipstick, or black oily slicks in the radiator or overflow tank. If the coolant is the color of a cup of coffee, that's very good - it means the cooling system sealer has been used.
    Also check trouble codes on the onboard diagnostics (see the sticky post at the top of this section for instructions).

    The 4100 got a bad reputation for several design flaws, most of which were resolved in the FWD cars of 1985-87. The primary problem areas are head and intake gaskets, weak camshafts, an overloaded distributor gear, and weak timing chain sprockets. But the truth is the catastrophic failure rate of 4100s under warranty was not that high. In fact, the 4.5 and 4.9 engines, which were updated versions of the 4100, remain some of the most reliable engines Cadillac ever produced. Plenty of people (myself among them) have driven 4100 powered cars for years with no serious issues. Mine gets 25 mpg on the highway and purrs like a kitten.

    The three keys to success with a 4100 are:

    1) Get a service history if one is available.

    2) CHANGE THE COOLANT EVERY YEAR AND USE THE GM SEALER SUPPLEMENT TABS.

    3) If you're mechanically inclined, purchase a Factory Service Manual for your year and model car. It can save you a fortune in labor.

    These are complex but not terribly complicated cars, well within the skills of the average shade-tree mechanic. By comparison, consider that large numbers of pre-2000 Northstar engines have similar head gasket problems, but they are so complicated hardly anyone but Cadillac dealers can even work on them. Head gaskets on a N* mean dropping the entire engine cradle out the bottom - thousands of dollars. On a 4100 - you can have the job done for less than a grand, or do it yourself for less than $400.

    Just go into it with your eyes open. Any old car is going to have things go wrong, and keeping a luxury car on the road is going to cost more than a Corolla. But then, a Corolla doesn't ride like - or have 1/100th the class of - a Cadillac.

  4. #3
    1987deville's Avatar
    1987deville is offline Cadillac Owners Member
    Automobile(s): 1987 sedan deville
    Join Date
    May 2005
    Posts
    68

    Re: HT 4100: Avoid at all costs????? Help!

    Great advice Noahsdad. I also own a 87 deville. Just turned 160,000 miles and basically everything on the car is original. 23mpg around town, 27-28 on the highway.

  5. #4
    PeteC is offline Cadillac Owners Member
    Automobile(s): 1987 Eldorado
    Join Date
    Jul 2004
    Location
    Hampton, VA
    Posts
    82

    Re: HT 4100: Avoid at all costs????? Help!

    Quote Originally Posted by 1987deville View Post
    Great advice Noahsdad. I also own a 87 deville. Just turned 160,000 miles and basically everything on the car is original. 23mpg around town, 27-28 on the highway.
    How do you guys manage that good gas mileage?

    My 87 Eldo with 53,000 miles gets 16 mpg town and 22 mpg highway.

    I have replaced plugs, cables, oxygen sensor, EGR.

    It idles a little rough and stumbles when I floor it.

    What else do I need to check.

  6. #5
    noahsdad's Avatar
    noahsdad is offline Cadillac Owners Connoisseur
    Automobile(s): '87 SDV
    Join Date
    Jun 2005
    Location
    Michigan
    Age
    55
    Posts
    1,296

    Re: HT 4100: Avoid at all costs????? Help!

    Quote Originally Posted by PeteC View Post
    How do you guys manage that good gas mileage?

    My 87 Eldo with 53,000 miles gets 16 mpg town and 22 mpg highway.

    I have replaced plugs, cables, oxygen sensor, EGR.

    It idles a little rough and stumbles when I floor it.

    What else do I need to check.
    A lot depends on the grade and quality of fuel you use, and on how and where you drive. The stumbling idle and flat spot could be a slight vacuum leak, or misadjusted or faulty TPS. Check trouble codes.

  7. #6
    JohnnyO's Avatar
    JohnnyO is offline Cadillac Owners Fanatic
    Automobile(s): '99 Eldorado, '04 DeVille
    Join Date
    Nov 2003
    Location
    Pittsburgh, PA
    Posts
    194

    Cool Re: HT 4100: Avoid at all costs????? Help!

    I worked at a Cadillac dealer in the 80's when those engines were new. The main problem we saw then was leaks from assorted places. With the zinc virtually gone from motor oil now, on older engines you are better off running a diesel-rated oil that still has zinc in it. Most are 15w-40 but if you dig a little you can find thinner oil if it gets cold where you live. I always thought it was a nice smooth-running engine with decent power for its size.
    Just keep a sheet of cardboard under it.

  8. #7
    PeteC is offline Cadillac Owners Member
    Automobile(s): 1987 Eldorado
    Join Date
    Jul 2004
    Location
    Hampton, VA
    Posts
    82

    Re: HT 4100: Avoid at all costs????? Help!

    Quote Originally Posted by noahsdad View Post
    A lot depends on the grade and quality of fuel you use, and on how and where you drive. The stumbling idle and flat spot could be a slight vacuum leak, or misadjusted or faulty TPS. Check trouble codes.
    The only trouble code I get is E048 EGR System Fault. The check engine light comes on infrequently (about every 2 weeks). I had changed the EGR last year.

    I am starting to suspect either ignition (have never changed distributor cap or module) or the fuel pump.

    If I can find a fuel pressure gage I will check that first.

    Any suggestions?

  9. #8
    HUF's Avatar
    HUF
    HUF is offline Cadillac Owners Connoisseur
    Automobile(s): 1995 FWB 100,*** miles CURRENT. 1991 Seville 175,000 SOLD
    Join Date
    Dec 2005
    Location
    MA
    Age
    55
    Posts
    1,997

    Re: HT 4100: Avoid at all costs????? Help!

    Quote Originally Posted by PeteC View Post
    The only trouble code I get is E048 EGR System Fault. The check engine light comes on infrequently (about every 2 weeks). I had changed the EGR last year.

    I am starting to suspect either ignition (have never changed distributor cap or module) or the fuel pump.

    If I can find a fuel pressure gage I will check that first.

    Any suggestions?
    A vacuum leak could cause EGR problem.

  10. #9
    tripledoil is offline Cadillac Owners Member
    Automobile(s): Cadillac
    Join Date
    Jun 2007
    Posts
    72

    Re: HT 4100: Avoid at all costs????? Help!

    Quote Originally Posted by caddymark View Post
    I am interested in a very clean 80's model Cadillac, around 60K miles, well serviced and pampered .... but with the HT 4100 4.1 engine. I have heard so many negatives about this engine. Should I avoid the 4.1 engine? There are other Cadillacs (and other makes) that I like from the 80's/early 90's that do not have the 4.1. What would you recommend? Avoid the 4.1? Thanks!
    God, when will Cadillac get it right? (never) Im going through all this BS with a 1999 Cadillac STS- So far Ive spent 10k on getting it right.....AND I was a Master Auto Tech only a few years ago- just not on Caddy's. A shop owner I know who has been in the businesss for 38 years said it the best. After the early-mid 1970's Cadillac is a 1 owner car. In other words, they are great for that large company CEO for 1-2 years.....after, a toilet on 4 wheels. To bad some look and drive so nice (if your lucky) - Oh ya, stay away from Cadillac "specialist" Custom Innovations in WI- take it from me. Look em' up on ggogle and read the posts.!

  11. #10
    tallpat's Avatar
    tallpat is offline Cadillac Owners Fanatic
    Automobile(s): 1986 Coupe Deville
    Join Date
    Oct 2006
    Location
    Columbia, Maryland, United Sta
    Posts
    130

    Re: HT 4100: Avoid at all costs????? Help!

    Alot of people bash the mid 80"s HT4100 engines Mine has 172,890 miles it was always well maintained never overheats. I agree it had some flaws in the engineering (a cast iron sandwhich aluminum block cast iron heads and aluminum intake ) you need to get a maintainance history especially on the cooling system. A well maitianed engine will last for years. In my case 21 years and going. Good luck

    Tallpat

  12. #11
    Po Pimp is offline Cadillac Owners Fanatic
    Automobile(s): 92' Eldorado, 97 Catera
    Join Date
    Dec 2006
    Location
    Tennesse
    Posts
    289

    Re: HT 4100: Avoid at all costs????? Help!

    There are a couple places that make the 4.5L to fit the early 80's configuration. These engines are way more dependable and have a little more power.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

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

Please enter a valid email address for yourself.

Log-in

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.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting