Engine overhaul cost

This is a follow up to a few other posts. Recently i stated I have reported my mechanic to the California Bureau of Auto Repair because he failed after having my vehicle for over 2 yrs. to give me a written estimate of cost to overhaul my v12 engine and transmission; When he finally gave me an estimate, he stated the transmission was $1400. Needless to say, I don’t know if that was replacing some parts or a complete overhaul. don’t think it was. just wondering if anyone has a “ballpark figure” what an engine overhaul should cost. Although I now have “written estimate” totaling $22,000 in total, I didn’t receive it until Dec. 2022, 2 1/2 years after dropping off my vehicle. That is the reason for my complaint which I recently stated to the mechanic. Basically, I’m attempting to get an idea what a reasonable estimate would be. I’m aware there are variables that might add or subtract from an estimate. The cost of labor, $9000 and “sublets” (?) $8000, is $17,000 leaving a balance of $5000 for parts. This may or may not impact the validity of my complaint but having some idea of the numbers may add ammunition, or not. His initial verbal estimate was $18,000. I’m well aware there may not be definitive answers, but a bit of thoughtful and rational input could be helpful.

Personally I would have thought that $22k is pretty cheap.

If you are a reasonable DIY V12 owner the parts to rebuild an engine can be from $1000 upwards depending on what is wrong and how far it needs stripping down. You can find ebay sites with new or second hand parts to help keep costs down, maybe somebody with a surplus set of new gaskets at half price for a start.
That assumes the bottom end is cleaned up but otherwise not touched which is feasible since there are few reports of damage or excessive wear in that area. Well maintained engines can give over 200,000 miles of reliable service with just a few wearable items like coolant pumps needing changed.
Many V12 cars are not driven much and you can plan a rebuild on the basis you only want another 2000 miles a year out of it, which dictates how far you need to go with expense and time.

A total strip and rebuild can take parts cost out to $3000+ if there is damage due to overheating, lack of oil or lack of inhibitor in the coolant and so on. After that expense you just have your own labour time which can easily be 100+ hours if you go to town on every little thing that can be replaced or tarted up whether essential or not.

The real trouble comes along for those who are not DIY owners. No easy answer there, you have to find a good Jag mechanic who can do a good rebuild job on the engine. Those mechanics are around in big cities in the U.S.A, the UK and Oz., just make sure you check their reputation.
If you cannot find such a mechanic maybe a better way to go is to have any competent mechanic at least pull the engine out and put it back in. Providing there are no other major headaches with old parts suffering in the process, that should not be too expensive. Then there is a choice to find a second hand engine from a reliable source, and they are typically $2000 - $5000, or freight the existing engine off to somebody expert in rebuilding V12s. If you tell the rebuilder you only want to get maybe 2000 miles a year out of it he can use his experience to just do enough work to achieve that. Then you might pay anything from around $5000+ to strip the heads and just replace things that are old and worn.

If the engine needs a total strip and rebuild to factory specs then you are looking at $15000+. For many owners that expense is just not affordable, not justifiable and not cost effective.
As usual the best advice for V12 owners in that category is to post their problem on this forum and check out the response before making any decisions.


I sometimes wonder about this…20 years from now when most of our V12 engines will need a rebuild, but used/low mileage V12s are gone, and mechanics with Jaguar V12 knowledge have passed, what will happen to our cars? Will they all be converted to electric?! In 2042, I hope some of our cars are still driving around!

There will be experts. And they will cost. There are still people who rebuild wwII aircraft engines. For a price.

When I recently inquired on this list about possibly stripping down a V12 engine I have,
I received a detailed answer from a guy that knows, that many vital parts for the V12 are NLA

I would not trust a Jaguar V12 to anyone that has not done many before (or with a lot of support from this list if it was myself)

Unfortunately for the OP, the answer I believe is “how long is a piece of string”

From my limited knowledge, a fairly complete strip down and measuring exercise would be required ( like almost any engine)

This may be a problem for the OP with the Bureau

How much does it cost to rebuild a Ferrari V12?..a heck of a lot I reckon

I spoke to a guy trying to sell a V12 XJ with electronic problems

He had already spent quite a lot, and was being mucked around and told he was up for thousands more. He asked $3400 for the non-runner, which was his bill up to that time, (with a Jaguar specialist)

Chris and Alan (Jaguar Services), for whom I was the unpaid part time apprentice for 10 years, have now shut up shop. Chris has rebuilt a lot of 6 and 12 cylinder Jag engines over the years.

When I was looking at buying an XJS race car 18 months I asked Chris what an engine rebuild would cost. His view was that if he did it with me around $20k, and probably double that for a customer.

As you say, it’s not just a matter of disassembly and reassembly with some new parts. It’s a lot of time in the machine shop and the very real possibility that parts of the engine will not be reusable.

Add to that the fact that any engine that needs a rebuild has problems already, and it becomes a complicated and expensive exercise.

Sadly this is exactly why the V12 XJS, excellent car though it is, is considered too much trouble by most workshops, and this reflects in their values.

Minimum price at CJ for a stock V12 is $25000.


Some of the answers point to difficulties the OP may have, as a “fair” price to rebuild a V12 could either be based on a “quote” such as mentioned above for $25k who is a specialist, and can estimate their average costs over a number of rebuilds to make a reasonable profit

Or an X$ per hour + parts needed agreement, which obviously cannot be pre-quoted

there are answers in this post that indicate the cost of parts

What Parts should I pull of a Carb V12 motor if I have to scrap it? - V12-Engine - Jag-lovers Forums

only a specialist with access to good used parts would be able to undertake a V12 O/H.

Its 100% clear to me that it could not and should not be attempted by someone that does not have contact to V12 Jag Spare parts, as there is just too many that are NLA (or very expensive)

I had “repairs” done to a V12, the specialist mechanic could not remove the head without destroying it, and used a spare off a dismantled engine he had, and that was 20 years ago

I remember him saying that he was most certainly the only mechanic in town that could fix them, and sneered that some pro mechanics who had tried had ended up sending them to him on a tow truck

As we know on this list, very old engines and fasteners can take a very long time to get apart. You could never charge the customer normal rates to cover it,

The Jag mechanic showed me an XK he was working on, saying the list was long as his arm, and all original old fasteners.

He is a race mechanic/ specialist high performance and in-house machine shop, so as you can imagine his hourly rates were not low

The Jaguar V12 is old technology. They were made pretty much like any other engine of the era. I have stripped and rebuilt 3 of them, not something I do to make a living. I don’t hold with the drama about parts no longer being available. The last V12 I rebuilt was just a spare I bought in case my convertible ever needs it. The engine was from a crashed car with no attempt at maintenance, something I found out as it was stripped. The heads were ruined by corrosion but brand new heads were available at the time 2 years ago. I had one badly scored liner and one badly dinged piston from a screw dropped into the engine at one time.
I easily found a second hand liner and piston here in Oz where the availability of second hand parts is much less than in the U.S.A or UK.
That engine is now as good as ex-factory spec.
Anybody with reasonable mechanical ability and a good set of tools can rebuild a V12.
It is time consuming but with help from the 2 main Jaguar forums you will find the parts and overcome any problems that seem baffling.
Before you start a rebuild check around for a second hand running V12 if you want a quick fix.
Like mentioned before you can get people to rebuild WW2 aero engines. Jag V12s can be rebuilt for another 50 years if there is a demand, just getting a little harder to source spare parts as time goes by.


Last winter I did a home rebuild of an MG engine. An XPAG from my 53 Arnolt. The total for outside services at the machine shop was about $1000. Total expense was about $12,000, just parts! The labor was all me. These engines regularly require a new crank, and I did do some upgrades, Plus ancillaries like carburetors…. It adds up when you do a first class job. I bet CJ won’t do a v12 for $25,000 that’s just a minimum.

This is why when your XJS just needs an engine, you just buy another XJS.

Hi Richard,

As I mentioned, several of our club members have rebuilt their V12 engines

However, as you mentioned, both used and new spare parts were required for your build

I presume you needed the steel plate tool to get the heads off ?

I am guessing you have skills well beyond the average owner

The OP implied he does not

Probably all the mechanics I know would reject such a job.

Of course there are numerous Jaguar mechanics in Australia that could do it for you, if you ship them the motor

I do agree a motor is just a motor

Our club does not have a steel plate tool, unfortunately, the owner wont lend it out anymore, as its become “bent” according to him

So if I wish to dismantle this motor, and sell it for parts, I first have to make the plate

one really has to ask their self… is this really worth it… there are so many options… labor is the real problem… it’s just four wheels that goes from here to there

The last V12 rebuild cost me around A$5000 for parts including 2 new heads airfreighted from UK. That also includes about A$1000 for outside work like linishing the liners and crank, and tanking the block to make it sparkling clean.
I could have saved A$1000 without sacrificing anything essential, but the money was not an issue.

One thing to keep in mind.
Techniques such as 3D printing, which is widely used for plastic items, is still in its infancy relatively speaking.
Well before 50 years is up you as a DIY engine builder, or a spare parts supplier, will be able to make one off or small batches of parts by printing techniques at reasonable prices. As long as you have a drawing or CAD file to suit. It will be a whole new industry.

Did not work on this engine. I put a jack between end of crankshaft and the head to get the front up a few mm. Then gradually fitted wedges between block and head.
Tried a plate but it would have pulled the bearing cap studs well before moving the head. Many hours of work.

Have we done a survey on this ? I reckon there would be a healthy % of owners who could rebuild a Jag V12 or I6 if they had too.

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Interesting, thats how the Jag pro destroyed my V12 head (busted out the cam studs)

I will re-examine this issue, I use a bottle jack to get the I6 head off

I do not believe I have ever seen a “poll”

I have a lot of tools and experience with engines, and have no concerns with a I6, and like I said, and engine is an engine, so I would try a V12 for sure

How many hours, machining and spare parts costs went into what you did, including searching for spares etc etc ?

As far as I know the bottom end of our club members V12 motors did not need attention

none were mechanics, but each was very skilled mechanically, with well equipped workshops

saw an interesting V12 rebuild Youtube, showed how the oil pump gets worn beyond spec

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From here.

  1. The mechanic is trying to save himself from BAR by writing t down.

  2. that mechanic wants you to pa for any work done and take the stff away. Just go away he don’t want yoou. a major eadache in his life. he knws that even if he compete the job, you wil; not be satsfed and wil cntnue to bad muth him