Hi all,

This is my first post on the jag forum. So Hello all! I'm completely green when it comes to jaguars. However not to cars in general and especially Audi's. I know my way very well around engines Go check out facebook.com/highoctaneracing for some of my projects

Since this week i'm the owner of a Dutch XJR100. Very cool car, however with an issue. A specialist identified an valveseat failure on front most left cilinder. Dunno wich cilinder nr that is.
It's still running but cr@p obviously. Like I said I'm new to Jags so any help from the community is much appreciated.

My plan is to remove the head and inspect what the damage is to that bank.
Secondly I want to find out if this is a common failure on these engines or if this is exceptional. If so then need to locate the cause of it.

I've found the repair manual for this engine on this website, so that should suffice for the teardown... One would also assume the engine can remain in the car when removing the head.

Would I really need the special tools or can makeshift/other tooling also do?

Again any help much appreciated to move this beast forward again.

Thanks,
Jeffer

 

Read that tools are must have. So found a set 99$ on ebay. Any good?

 

Also read through this thread. Looks like a common failure due to overheating
https://www.jaguarforums.com/forum/x...ow-4747/page3/
Looks like a complete teardown to me. Replacing all vale seats to reassure it won't happen again anytime soon.

 

It probably means it was waaaay overheated if there are dropped valve seats... I would look for a good used motor to swap out as a severe overheat can damage other things as well.

 

Can you give us a set of compressions please? Are there any leaks in the cooling system? or oil leaks? Have you scanned it for codes?

Maybe the crank pulley slipped, seen that done, you'll be undoing the crank pulley bolt to get the timing cover off so check the torque from memory is 385Nm. You may need to heat the bolt but be careful not to cook the crank pulley, its a rubberised damper unit.

The AJ27S engine shares the later timing gear off the 4.2 units so the chains look different but the 4lt heads are switchable, I'd be inclined to swap the heads using 4.2 gaskets. You can unbolt the cam sprockets and switch those inc flywheel to the fresh heads. Why not give them a polish and port.

Cam reluctor lobes are different from AJ26-7 - you'd need the 27 variant because they have 2 cam sensors, not 1.

This would save machining and shimming.

The obvious stuff like thermostat, waterpump, belts, coolant rez and hoses, the breather bottle for the coolant etc etc all need a good inspection on the strip. I can only recommend Jaguar OE parts on engines so your rebuild bill is going to be 3rd the value of the car. The head swap route V finding an engine may be faster and easier and cheaper.

 

Thanks for the pointers. I will share the first diagnostics as soon as I start on it. Also a specialist has looked at it by the previous owner. I will give him a call to discuss his findings.

First off, is taking the heads of and see what we encounter and take it from there.


What are 4lt heads? Sorry for my ignorance.

 

Before you remove heads take a set of compressions. You can tell if the engine is toast before you commence serious work.

AJ27 (Engine code) 4 litre N/A and 4 litre supercharged have the same heads, wider scope for a parts search.

 

Sean, i will perform the test next week and will share the results. Ordered the valve cam locker tools. So soon i can start on it. No rush because it isnt my daily driver....

 

Hi all,
Just had thebcompression check on all cilinders. Front cilinder on rh bank has 0 compression and clear marks left by debris on the plug. Bad news in my book. All cilinders on 8 bar except the rear most cilinder lh bank has 7 bar. Still not catastrophic.

All plugs have bent electrodes on the rh bank. Wich indicates debris has traveled through the intake to other cilinders.
Ive ordered the tools for cam timing. So next job is lifting the head to see the carnage.
Any pointers for removing intake / sc / head? Or just as any other car...
Cheerio!

 

SC removal a pain, threads discussing it on here and XK8/R forum. The exhaust manifold comes off with the head.

 

+1 on the S/C find a long 10mm flex head ratcheting spanner for the rear bolt to avoid lots of swearing...take pictures as you remove each lump.

Getting the timing cover off can be a pain and you'll need a very good pulley puller chase up a loan on here by searching for crank tools rental you are warned that using the cam locking tool that goes in the rear of the block where the crank sensor lives can and does bend the timing plate so a pulley holder is an essential. Cam locking is 45 degrees after TDC.

The crank damper unit has a little o ring you'll need to replace and check that the cone/crank nose isn't damaged if it is a slipped pulley, you may need a new cone and certainly a new bolt as they're done up super tight (stretch torque).
Once the front timing cover is off it's lift the heads and if the head bolts are not centre popped/marked you can reuse them
Soak the exhaust manifold bolts with WD40 type stuff and keep flooding as these sheer off and you'll need some spares they break easy.
Lots of engine connections at the rear, tb, fuel sys, ecu keep as much connected and labels help with the vac lines.

Why not make a thread of it and include pictures of your rebuild? I for one would like to see what's happened once you pull the heads.

Finally the small diameter water system tubes, 2 small screwdrivers to open the norma connectors, be careful with them because they break easy too

 

Thanks for the toptips guys. Ill try to locate that pulley cranklocking tool. Is it something i can fabricate myself? Ill start a newbthread when i get on it. Currently some other builds require my attention first. First finish those.
Thanks

 

Next week we pull the engine from the bay. Then I do a full stripdown to see the damage and make a plan of attack.

 

Hi ll, Just checking what option would be best. Curruntly all the engine connections are detached and the enige is ready to be pulled. The aircon compressor disconnected and gearbox disconnected. Already got all the gearbox bolts undone. Just missing the fuel line tool to disconnect the fuel line.

However what would you guys do, pull the engine with gearbox, or detach it from the geabox?
What are the pro's and cons?

Thanks for the help

 

At this point, since you have it all undone- just the engine.

 

Thanks. We continue saturday with pulling the engine.

 

Hi Jag members,
Well tehre is news on the engine. The valve seat dropped in the engine and created havoc on all 4 cilinders on the LH bank.
The front cil has the most damage obviously because thats where it dropped. The others have seen debris that traveled across the intake. So now I need to source at least 2 pistons. And have either the head overhauled or find a replacement head.

I'll tear down the engine further and give a compete overhaul. Bearings, gasket ect etc.

I've found some heads on ebay but i cant judge if these will actually fit the engine?
Any help would be much appreciated finding bits.


Thanks

 

sorry forgot the pics....

From what engines can I source pistons and heads?
I've seen some S-type 4.2 pistons on ebay. Would these be the same as the aj27s pistons?

Same goes for the head.
Thanks!

 

Hi, Small update. Decided to strip the engine completely and give it an rebuild. I've measured the clearances in the engine and all looks good. The replacement cil head is already in. While i'm taking it apart i like to adres the cilinder heads for more power. So a mild cilinder port for more flow and i'm thinking of adding a powerhouse lower pulley.

My list to replace so far are:
Piston rings
rodbolts and bearings
main bearings
headgasket set
valve seals
4.2 MLS headgasket
coolant hoses underneath the SC
Thermostat
plugs
chain guides look fine so won't replace those.

Supercharger service?

I'm not on a huge budget but I like to do stuff right straight away.
Is there anything that isn't on the list and would be highly advisable to replace while i'm at it?

Thanks,
Jeff

 

I'm 99% positive that I've found the issue. The coolant sensor has broken on the main watermanifold. It's a small m12 temperature sensor and its broken clean off. It's probably been broken for a long time deu to the corration traces.
This will defenitely fool the ecu in both ignition timing (advancing/retarding) and injection opening times.

Also a chain guide was broken off on the primairy chain. Not the full guide but the lower corner of the RH bank guide. It snapped of and ended up in the oilpan.

All bits are ordered to rebuild and next week i'll reassemble the entire lot.

Cheers