minimum hours needed to replace head gasket
 

Hi, I have an exhaust valve stuck open (possible broken spring or dropped valve seat). Zero compression in cylinder 6. Shaky idle but fine otherwise other than ticking sound.

A shop quoted the labor as 18 hours just to remove head, change gasket, and replace head.
Of course lots of other costs involved to repair head and valve seat if I didn't find a used head with all valves in place.

Does it really take 18 hours to follow these detailed instructions? Has anybody here done it in less than 8 hours, if nothing is stuck?
(No supercharger on my engine)

"How the change a head gasket on a Jaguar X300 Non Supercharged Engine"
https://www.jaguarforums.com/forum/x...ne-faq-114960/

thanks!
I wish I could just plug that exhaust valve hole from the exhaust manifold and see what happens with just one exhaust valve :)

Hi madijag,

It's been awhile since I did a head gasket, but I've never done it in less than 8 hours. To do so would probably require everything to go perfectly, and that never seems to happen for me!

According to NAPA's repair estimator guide, labor for head gasket replacement on a N/A 1996 XJ6 would run $947 to $1208 in my area, implying around 9 to 12 hours at $100 per hour (the common rate at independent shops in my area), or perhaps fewer hours at higher dealer rates.

While tasks like draining and refilling fluids, bagging and labeling parts or organizing them in some other fashion, and labeling electrical connectors are not difficult, they do take time, time that accumulates significantly on a big project like a head gasket replacement. A good mechanic approaches a job like this methodically, not as a race, because even one small mistake can mean having to do it all over again or causing fatal damage to the engine. Do you really want a mechanic attempting a world-record time for reinstalling your cams and timing chains, or torquing the new head bolts? I think 9-12 hours is a reasonable estimate, allowing for the kinds of things that always seem to happen when working on 20-year-old engines (broken vacuum hoses, brittle electrical connectors, etc.).

By the way, this will be a great time to check, clean or replace normally difficult-to-access items under the intake manifold like the oil pressure sensor/transducer/switch, oil filter/cooler adapter gaskets, oil cooler/bypass pipe O-rings, dipstick tube sleeve, etc.

Cheers,

Don

Jaguar warranty time for 4.0 Engine cylinder head gasket replace (VIN 739427 to 812255) is about 6 hours.
Real world time would be 'warranty time, times time and a half' or about 9.0 hours. (6 x 1.5 = 9).

You would need to add repair time to that for valve(s)/guide(s)/seat(s) at a machine shop.

Setting the valve clearance or 'lash' if an actual 'valve-job' is involved would add to the parts and labor accordingly.

Since the engine is decades old, I would expect shops to add additional hours for rust, corrosion and generally dirty parts.

bob

Shop elsewhere, can't see why this would take so long just to swap head, even first time I did it, it took 14 hours and I did it with Haynes only and 0 experience. I would think you could find someone who could do it in around 10-12 hours for sure.
Why not try it yourself anyway? It's not rocket science, just nuts and bolts.

I did one last year and I can tell you the problem is that there is an incredible amount of peripherals around that head. You begin to appreciate just how much of a lunatic the designer was. I have done them before on Alfa Romeos and it's pretty straight forward. This? You need the patience of Ghandi for this one. This is a hobby for me so no rush. After 4 days the head was sitting on my workbench. Sounds like you have a broken spring. May as well do a valve job on it while it's out. Reassembly is a pain also. The head weighs a lot and the gasket is fragile. As you reinstall the head there is always something in the way that may lead to a ripped gasket. The local mechanic quoted me $3000- for the job without the valve job. So you can see why I did the job. She now runs like a new car.