Looking to buy a Seville for my semi elderly father (headbolt question)

[LoveCaddies]

Ok, am I to understand the Northstar powered Cadillac's 2004 and up have resolved the head gasket/ head bolt issue? I have always loved the looks of those Seville's but after all the car's we have owned, we have steered clear of any late model Cadillac because they are money pits with that head gasket issue. Has that been resolved in the 2004 and up?

I do own Cadillac's, have had several 60's and 70's. Currently we have a 1961 Cadillac S & S Victoria Hearse which is receiving a rebuilt 512 Cadillac. All black , all stock with her wide whites and fender skirts. Thanks for your help everyone, we are looking to possibly get into a Seville here soon.

Any issue's you can give me a heads up on when looking at used Seville's, im looking at some under 100,000 miles, any trans issues with these? suspension? and expensive quirks these cars have?

[Cadillac Jim]

Caddyinfo is a major go-to web site for people with problems with their cars or dealers, so we get a large portion of the people with head gasket problems. That sort of skews the statistics toward having a higher percentage of people who have any particular problem. We have a survey page on people that have had that problem fixed:

http://caddyinfo.ipbhost.com/index.php?showtopic=4942

Note that it shows 15% of respondents to say that their car has been Timesered (or equivalent), e.g. had a head gasket repair. Although this is not a scientific survey, it is hard data that head gaskets don't automatically go on all Northstars, or even a very high percentage. When they do, its a major problem or a disaster, of course. It happened to me.

If you ask people who are having head leakage about changing their coolant, nearly all have never done so, don't remember, bought the car used and don't know, or have been seven years without changing the coolant, as my car was. The Dexcool antifreeze is advertised to go 150,000 miles or 5 years, whichever comes first, and people tend to think 150,000 miles and let the five years go by, as I did. We did the same thing with my wife's 1999 Pontiac Grand Am GT, with an HO version of the corporate 3.4 liter V6, and we have had the intake manifold gasket replaced twice, a major job requiring that the pushrods be pulled on that engine, for the same reason. Letting the coolant go too long in any aluminum engine will cause disaster. In a Northstar, it takes the coolant about five years to go acidic, and another two years to cause a head bolt to pull out.

The 4T80E, sold only on Northstars, is a known brick. Other than shift solenoids (not a big job to replace), the worst problem you can expect with a 4T80E is a TCC failure, which requires a new torque converter. If you disregard dealer advice and have your transmission serviced occasionally, you should not have any problems with a 4T80E.

The Northstar has been updated a number of times since its introduction in 1992 for the Avanti. In 2000 the redesign included roller rockers instead of direct-acting cams, a combustion chamber redesign that allowed better performance if you choose to use regular gas, and a change in the head bolts. There was another change in the head bolts in 2004.

If you buy any used car, you should test the coolant for being too old, and not buy a car that has not had it coolant changed in too long. That applies to any make with aluminum heads and/or block, which is to say, all of them these days, from Volkswagen to Veryon. In the case of a Northstar, the coolant test should include a test for combustion by-products.

One expensive item in high-mileage cars is the cost of struts and shocks. Many people choose to disable the electronic suspension and put less expensive shocks and struts on their car when the time comes, but my preference is to keep the features that make driving a Cadillac so attractive. Monroe and others offer reasonably priced electronic struts and shocks for older Northstar cars now.

[LoveCaddies]

Hmmm ok good info thank you JIm, can you elaborate on this combustion antifreeze by products test? so a 2005 Deville which has been taken care of should be a reasonably safe bet you would think?

[Texas Jim]

Hmmm ok good info thank you JIm, can you elaborate on this combustion antifreeze by products test? so a 2005 Deville which has been taken care of should be a reasonably safe bet you would think?

The headbolt issues were pretty well eliminated with the last revision of the bolts in 2004.

A 2005 should be a pretty safe buy.

If "I" were buying it... just to on the Ultra Safe Side.. I would go to my local AutoZone and rent the combustion byproducts test kit... it is only about 10 bucks.

Do the test and if it is negative, which it probably will be, and everything else checks out on the car, I would buy it.

THEN I would have the coolant changed and the transmission serviced.

THEN I would drive it and enjoy it...

[airmike]

I thouroghly agree with Texas Jim

[Cadillac Jim]

The first thing to check in a used car is the CarFAX or equivalent. Before you buy any car you should have it checked out by a competent mechanic. There are services that do this for a fee of about $100. If you do that the inspection should include testing the coolant for being at least 50% antifreeze, having DexCool or the equivalent (not green!), and combustion by-products - but ask, if you use such a service. If it's less than 10 years old, a dealer may be a good place to get an inspection.

Yes, when you get any used car, you should have the coolant and oil changed and service the transmission. The pre-buy check should tell you about the brake fluid, power steering fluid, hydraulic clutch fluid if applicable, and the condition of the belts. If it has a timing belt, change that too (the Northstar does not; it has internal timing chains that don't need periodic replacing). The pre-buy inspection should also tell you about any other maintenance items, like brake pads, missing undercar shields and air dams, etc.

[KHE]

I'm not convinced on the Carfax thing. At $30.00 per report, they are pretty pricey for what they provide. I had my local Chevy dealer run one for me when I was verifying the mileage on a used transmission I was looking at buying for my STS and the last mileage reading was over 10 years old! I obtained much more information by having them run the VIN for the service history. I would have been upset if I would have paid $30.00 for the Carfax report.

[joeb]

04 was last year of FWD Seville. The DTS continued on. So u can find a newer, more expensive FWD caddy if you wish. What is your main factor? Low miles? Price?

[LoveCaddies]

Ok thank you for the info Caddy Jim and Texas Jim great points ill take with me when we go to look at some Caddy's =)

Joeb, my main factor is finding one with less than 100,000 miles, well maintained, ideally I'd like it from a senior so I know that it hasn't been driven hard and its been taken care of, of course price plays into the equation, I don't want to pay 9 grand for one that isn't happening. So 2005 and up is rear wheel drive? seriously? I'd love that.

[KHE]

So 2005 and up is rear wheel drive? seriously? I'd love that.

2005 and up STS is rear wheel drive. The Deville/DTS remained front wheel drive until the platform was dropped at the end of the 2011 model year.

[LoveCaddies]

Ok good!!! looks like we're going to start looking at 05' and up STS's , I'd love to have the rear wheel drive platform.

[joeb]

Well, your comment of not paying $9k and <100k miles for a 05 or newer STS might be difficult to achieve. Also, if u compare 97 deville floaty body, roomy interior to 06 Sts, small interior, tight suspension u may be disappointed. U need to drive a 06 Sts and get a feel for it

[LoveCaddies]

Well Joe I've been seeing some 04-08's in my area going anywhere from 3500 to 9000 grand area, I'm hoping I get lucky and patience will play me a lucky hand in obtaining one. I also don't think the old man would get nick picky about a slightly smallish interior and a tighter suspension, as long as it still had that Caddy ride we'll be ok, hell he's driving around in a RT Challenger right now and it's not exactly smooth on the bumps lol, anything will be an improvement.

[LoveCaddies]

Ack, wait no. Those STS's are V6 rear wheel drive, that just wont do. I was thinking they had the Devile DTS sort of styling. No those are out of the picture unless there's a V8 in it.

[LoveCaddies]

Oh wait never mind I'm sorry. I saw the v8 version.

[Cadillac Jim]

The premium V6, particularly the DI version, is 300 hp and over. With the six-speed transmission, they are more than acceptable. Drive one before you decide that they "just won't do."

[sonjaab]

Another thing is if that car is at a GM dealer just have them run a VIS report from their GM computers.

This will list any and all warranty repairs, maint. services, or any complaint by the prev. owner to a

GM dealer.

Also most dealers will run you a FREE Carfax or Autocheck report (depending on which they use).

[barczy01]

The head bolt issue was not fixed. Yes, they went to a coarse thread but it backs off over time. I have done 5 of the new thread design already and they were loose.

[Tony S45]

barczy01:

Two questions:

Can the Northstar head bolts be periodically re-torqued in proper sequence reducing the potential of a head gasket failure?

If the answer to the first question is yes, can the new design head bolts merely be replaced into an older Northstar and then the heads re-torqued or must the new thread design be tapped into the block when the heads are removed from the engine?

Thanks.

[KHE]

There is a microencapsulated threadlocker that is applied to the head bolts when the head bolts are manufactured. Once the engine has thermo-cycled, you can't tighten the bolts or you will break the bond of the threadlocker. If the bolts are loose, the heads need to come off, inserts installed and new bolts installed.

The thread pitch and length has changed so you must use the year specific bolts for the application.

[Tony S45]

Caddyinfo:

Ok. Thanks.

[Cadillac Jim]

The head bolts aren't the problem. When the five-year coolant goes too far past it's limit, it goes acid. Trace amounts of acid coolant find their way to head bolt wells. If it's acid, galvanic action between the steel bolts and aluminum head will eventually weaken the threads. Eventually, a head bolt will pull. This typically takes about seven years without a coolant change.

If you maintain any Northstar well, including changing the coolant every four years or so, you shouldn't ever have a pulled head bolt or head gasket issues. If you buy a used one, check the maintenance history. If the coolant was changed by a dealer, any Cadillac dealer can see this with a maintenance record check using the VIN.

If you are looking at a used Cadilllac (or Buick, Pontiac or Oldsmobile) with a Northstar, or in fact any used car with an aluminum head or block or both - which is about any of them these days - you should check the coolant and have it tested. If you have a DVM, you can connect one terminal to a good ground and put the other in the coolant. If the DVM reads 0.7 Volts or more, the coolant has gone acid.

[barczy01]

Jim is correct to a point. The new coarse bolts work there way loose overtime. No, you can't switch from coarse to fine without drilling the block and a total disassemble the engine. I have encountered many virgin blocks where all the bolts are tight but the dexcool has eaten the head gaskets. Look at my pictures in my EBAY Ad.

[Cadillac Jim]

The head bolt wells are sealed at the factory explicitly to resist any traces of coolant, acid or no, and apparently if this holds 100% then the head gaskets can get pretty bad without a head bolt pulling. I expect that the overheating symptoms will be a bit different than those where a head bolt has pulled, but only by degree in the situation where the engine overheats right after being under heavy load.

A place that does a *lot* of Northstar rebuilds like barczy01' shop will see rare events that we don't get often even on Caddyinfo.