Tow the car on over I'll help you.
I have nothing but time on my hands right now.

 

Without pulling the camshaft I do not know how one would get the covers off of the valves?You can see it in the photo you have to pull them off to even see the valve spring?

 

Yes you would have to pull the camshaft off just to get to the caps over the valve spring.
I'm just thinking out loud here.. I've done this stuff before on other cars.
With time and patience it can be done in your garage or driveway..
Plus you'll have the help of these guys here with any questions.

 

That's a picture is the top of the valve . After the camshaft is removed. On the left it's with the cap removed they just lift off. Exposing the top of the valve spring.
I'm pretty sure. Hope someone else will correct me if I'm wrong.

 

If you have a bent valve or dropped valve seat the valve will not return and there will be a noticeable difference in the gap between the adjusting shim and the cam. I think a broken spring is less likely with these engines.

 

He'll have to decide how far he wants to go, if it is a bent or bad valve / vakve seat. Then the only choice is to remover the head....
and send it off the and shop.
Which to me isn't that big a of a job once the intake is removed.
or let a repair shop do it...
its not that uncommon to have a 2nd mortgage these days.


jay

 

to see the springs you must take off the bucket. the sides are covered. 99 times out of 100 it’s a dropped seat not a broken spring it’s gotta come out.

 

To remove the valve springs with the head on the car you need one of these.

 

That's a handy little tool, but I think he doesn't know for sure if it is a broken spring or bad seat or even a bad valve. I believe replacing the spring itself isn't a big deal. If the seat dropped then the head has to come off. Then Hopefully its just the valve seat and maybe the valve, just needs to be replaced.
Hard to say without seeing anything.
that's my 2 cents.

 

That tool is for a traditional OHV with rocker arms design.

 

Good to know RJ.

 

Sorry for the delay. Decided to purchase an endoscope camera that plugs into my computer from Amazon for 50 bucks. It arrives on the 22nd and I'll hopefully have an answer. I'll post photos to show the results.

 

You could put an endoscopic inspection camera borescope down the spark plug hole and have a look at the valves before contemplating any dismantling. Anything less than a loose valve head stuck into the piston crown is good news.

Graham

 

That's why I ordered one. Makes a lot more sense than pulling the head off . There has to be reason for zero compression when all others are 200 to 225. I closed the valves and blew compressed are through the spark plug hole and got a lot of air out the throttle body so it's why I suspect an intake valve and why I bought the camera. I also found a piece of carbon on the plug and am hoping the previous owner's overheating incident dislodged some from the piston and a small piece is sitting on the valve seat. Nice if I could remove it using the included hook on the end of the camera.

 

And people here wonder why I preach on getting that crankcase ventilation OUT of the intake tract Or at least use a catch can. The carbon build up caused by routing it back into the engine does damage in more ways than you think. Keeping valves from seating is just part of it. That carbon on the pistons doesn't need to break loose and hang a valve. It can get hot enough to glow red and cause detonation too. It also causes detonation by lowering the octane level of the intake charge.
The valve faces have just as much carbon on them as the pistons do, btw.

 

@Alderbrad, if you've removed the cam cover(s), what is the condition of the secondary timing chain tensioner(s)? Are they metal or plastic bodied?

Have you checked the camshaft timing to see if it's correct on the bank with the cylinder having low compression?

 

No I didn't take the cam covers off. I just wanted to diagnose the issue before I decide my direction. I picked it up from the proverbial little old lady, a retired school teacher who just had enough of repair shops ripping her of. It's an otherwise mint condition low mileage Carnival Red Vanden Plas with Avanti 18" wheels as well as the Jag wheels both with new Perellis. Documented from purchase in Florida and she's second owner. The specialty tools are an issue but I am a retired mechanic on a disability pension with a shop so repairs aren't an issue. Do I want to dive is is. So if it's a blocked seat from carbon or a dropped or bent valve, or broken spring I'll likely buy the balancer puller tools and do it. I just want to take a look with the camera first and see. I expect if it was a piston issue I would have gotten air through the crankcase instead of the throttle body.

 

So I am not reaching on the possibility of carbon blocking one of the intake valves from seating then? It's the carbon I found welded to the plug that lead me to hope it's that simple. I will certainly take your advise if I repair it.

 

No, it's not a reach. Take a look at Vonnssingo's pic in post #17. That is a classic example of exactly what I've been talking about and it's totally 100% PREVENTABLE!
It's carbon buildup from oil and crap that doesn't burn for chit and isn't meant to burn in the combustion chamber. If pieces of that get broke loose it can certainly keep a valve from seating among other problems. Once it gets that bad it tough to get it cleaned out short of disassembly too.
You can steam it out but run the risk of the same thing happening should a piece get lodged in the wrong place.
I have successfully steam cleaned combustion chambers tho spraying a steady mist of water in the throttle body once the engine is up to temp. Watch the black chit roll out the exhaust pipes. Not a pretty sight. Be sure to keep the engine from clonking out by the keeping the rpms up high enough.
An engine should never get that carboned up.

 

Removing the cam covers and inspecting the secondary timing chains, guides, tensioners and cam timing are part of the diagnosis procedure on the AJ27.

If the secondary tensioner on the bank containing the cylinder with low compression has failed, the exhaust cam may have jumped one or more teeth. If the exhaust cam has jumped more than two teeth, there is surely a bent valve.

If there is air coming through the inlet manifold, there may be a dropped inlet valve seat.

Here is a link to the engine training course that you may find helpful:

https://www.dropbox.com/s/vqpy3bbjzd...e_168.pdf?dl=0