Gurus,

in my effort to step-by-step troubleshooting of my lack of acceleration issue chasing just about every other issue previously - fuel pressure, vacuum leaks, throttle body, O2's, wiring, MAS, Coils, Plugs, yada,yada,yada, I removed the intake manifold to check the intake gaskets. The intake gaskets look like they had been rolled over non-uniformly and were probably leaking, the next step was - while I was there - to check if the timing chains had skipped, along with compression checks / leak rate. Cam timing is spot on, cam flats match on both sides, sprockets look in new condition - flat top unworn sprocket teeth), no looseness in the chains.

Anyway in this process, it looks to me the engine has had some sort of update first hint was different cam cover gaskets than OE, but the secondary tensioners are the orange plastic ones - not cracked or broken (yet), however all chain components look relatively unworn and not extended which for a 2001 XJ8 NAS AJ27 engine (VIN F23776) with 106k miles I would expect to see some extension and at least some indication of wear.

My question is before I go tearing apart the front of the engine and order a full timing chain set with upgraded metal guides and tensioners, the timing chain guides in this engine are Gold color, not dark orange plastic ones like the others I have seen that are cracking - self destructing.
Does anyone know if the factory may have updated the chain guides as gold colored plastic (maybe these are actually gold color anodized aluminum?) or are there aftermarket - known/unknown quality that are gold colored plastic or gold colored anodized aluminum that might have been installed? Note the guides seem to be the exact same color as the gold anodized nut in the 3rd photo.

outer primary chain Guide

Inner Primary Chain Guide rear of chain view

Inner Primary Chain Guide front of chain view


Thanks in advance for your expert eyes!

Cheers!

 

I have no knowledge of the gold colored tensioner guides, but the guide in picture #3 looks to have a very obvious crack in it and is ready for replacement, which would probably indicate that while the orange plastic tensioners.may look good, you may find they are also cracked once you remove them.

 

Thanks CK.

One problem with photos, the photo lighting and shadows are nothing like the in-person eyeball.

What appears like a crack in any of the three photos are actually are casting mold lines, pic #3 has a small void - that looks like a crack in the photo. That void has been probed with scribe to see if it was falling apart and it is definitely solid.

 

If you're unsure of the primary timing chain guides and tensioners, it's best to err on the side of replacement. Many look good from the top with the cam covers removed, but are usually severely cracked or broken once the timing cover is removed for closer inspection. When they do break, pieces fall into the sump.

The secondary tensioners must be replaced with the newer metal-bodied versions. Use the correct tools and procedures detailed in the Workshop Manual.

 

Ah yes,I can see what you mean, looking at it after reading your description I can see how it is a casting protrusion not a crack depression. Like one of those revolving mask illusion things!

In that case............I'm at a loss.

I haven't heard of the gold tensioner guides, but if your actual tensioners are the red plastic type, I would assume they are the originals?


.

 

As per NBCat, the tensioners can look perfectly okay when viewed with the cam covers removed, but a different story when they are disturbed. Mine looked fine, but when I removed them this is what I found. (Pic below)

Definitely a good idea to replace all 4 tensioners and guides, as well as chains.






.

 

I did a scribe scratch test on the upper and lower and they appear to be "al-u- min-e-um" ... aluminum.



Lower Guide scratch test - aluminum

upper guide scratch test - aluminum

So now the issue is, the primary and secondary tensioners appear to be red plastic, OE versions in early engines probably known to fail (gee sounds like Stag Timing Chains issues from almost 50 years ago)
and the guides are aluminum, chains look like new as do the sprockets. So I wonder, this is a late 2001, what are the chances these are OE factory or replaced somewhere before 86k miles when I bought the car?

Should I leave it as is, replace the Tensioners only, or upgrade to the latest multilink primary chain /gears/sprockets, guides and tensioners? Aftermarket, Lincoln LS 3.9 or OE Jaguar? It is not like this car is a showpiece, it has slight hail damage, Previous owner damage that was poorly repaired, and I have a second one in the driveway also a daily driver anyway..

However on the significant upside, there is a guy on Ebay in N.J selling complete updated aluminum timing chain kits for $69 that appear to be Lincoln LS sets, so I am wondering if there is a cheap aftermarket for the parts or if the Ford bagged parts are just much less less cost than the Jaguar OEM bagged parts?

I am going to think this one over for a while ...

 

If you're suspecting cracks, I'd definitely look at replacing them soon. I got my car as a fixer-upper with known timing issues, turns out one of the primary guides had cracked into pieces, and while doing so sheared one of the primary tensioner bolts flush off in the block. I couldn't see much of this from above when I had only the timing covers off. That bolt was a scary thing to see when I was pulling everything apart, fortunately that came out easily.

The new guides that I got were a similar design with a plastic sleeve over a metal core, but with much more material and a slightly different setup. I think the "red" is staining from oil, the new ones were a light brown color. I'd look at getting one of the newer style kits with a Morse style chain etc, would look to someone else for the exact compatible kit type though, it gets confusing when looking for those parts.

EDIT: something like this one? https://www.ebay.com/itm/Timing-Chai...L/282962239621

 

Be aware that the Primary Timing chains To Engine (0108122359) are the normal roller.
The Primary Chains FROM Engine (0108130000) are the 'Morse' silent running chains. The sprockets and guides are also different.

The eBay kits are offered in both styles, you need to pick the correct one.
ALL the secondary chain/tensioners are the same.

bob

 

Well after a full valve timing/clearance, compression test and then leak down test - all greatly facilitated by removal of the intake manifold, the timing chain/tensioners issue is now secondary - that all needs to come out anyway.

After verifying the valve timing was correct, I rolled through measuring all the valves which oddly enough, all were within cold spec, intakes at 0.008" / 0.20mm and exhausts at 0.010"/ 0.25mm. I fully expected to find at least a couple out of spec and I found two intake valves at 0.010"0.25 mm which were ones probably carbon fouled. I am quite surprised to see that this engine has non-hydraulic valves and still retains manual shims for valve lash adjustment, and, I am very surprised at the similarities this engine has to my 50 year old OE Triumph Stag 3.0 liter V8 for timing chains and valve train - tappet buckets with adjusting shims under the OH cam, timing chain primaries, etc. Sure there are modern upgrades in the all aluminum block layered stack design, but many of the basic engine OHC designs are the same.

Compression tests were not good at all. Best cylinders were 115 psi relative to my compression tester with a long hose, and #3, #5, #8 were 70/80/90 PSI, so next step was leak rate.
Starting with #1(1A), both intake valves were blowing by when fully seated, so there is most likely carbon swarf under those seats. A test of the rest of the engine found similar results, intake valves and exhaust valves leaking randomly (by my leak rate on an average of 20% - 50%) , and of course some showing leakage past the rings - completely as expected in a fully cold engine with minimum lubrication in the cylinders - some top end oil reduced that to determine most of the leakage is in/out valves. None there were leaking into the coolant indicating blown head gaskets. The hint here is that the valves are in spec for timing, but the diagnostic sign is the carbon buildup in the intake ports in the intake manifold and cylinder head, but fuel economy never seems to be less than 21 mpg USA as typical. Leaking injectors? There is no evidence the injectors were ever leaking, but the intake valves leaking would likely have some blowback on the compression stroke, lower compression causing incomplete stoichiometric combustion and excess carbon, but not detected by the knock sensors. These AJ27 engines with VVT do not have EGR paths to carbon up because it is supposed to be compensated for by valve advance/retard, so I am wondering if the VVT are fully functioning - more tests there too.

So next step is of course, heads off for a full cylinder bore inspection which on this 2001 AJ27 engine is supposedly full steel liners. Then if the cylinder bores spec out and I do not see the problem Land Rover had with their steel cylinder bores shifting, then if the heads are good, decarbonizing of the pistons, and heads if they spec out, R/R the valves check for bends and seating, and fingers crossed - all that is needed is to decarbonize the heads and lap in the valve seats.

I am glad I held off with ordering the timing setup as now I will need head gaskets, valve guide seals, all the other seals for replacement of the timing chains ... and whatever else might be needed, but I will hold off until I see if the engine is worth rebuilding the top end of it this will become a 2001 XJ8 parts car.

Cheers!

 

What I have seen on my 75k miles heads and the 36k miles heads that I bought as replacements (my original heads were overskimed) is that all valves had quite a bit of pitting on their sealing surfaces so I had them re-faced before lapping them in. On the other hand, all valve seats were very good with no pitting at all.

 

That is interesting that the valves were pitted at those low miles.
Thanks for the heads up. Resurfacing the valves I'll need new shims on setup, anyone have a good selection of shims?

Wow, overskimmed heads at 75k miles, who would have thunk?
Do you have any OE head thickness?

Who knows what I will find when I tear this down, I would think any dealer repairs were warranty before 36k miles, anything after that up to 86k is unknown and surely to be quite a surprise since this has unknown Gold anodized guides ...

 

Pitting of valves appears to be "standard" on these V8 engines. I saw a post (probably on this forum) by a member talking about the same thing. When you clean the carbon/gum off, the valve sealing surfaces may look ok when casually looking at them but, under magnifying glass, you can see the "surface of the moon". I tried, but the pits could not be smoothened out just by lapping. As for the shims, you can swap them around and end up needing just some new ones.

My original heads were skimmed probably a number of times by the PO struggling with the Jaguar "specialists" in Malaysia. Why he could not get the head gaskets seal well was because the "specialists" reused the head bolts (god knows how many times) during multiple gasket replacements, overheatings in the meantime (it did not have a thermostat !? when I bought the car = running hot all the time). Furthermore, I found that more than half of the head bolt thread inserts in the block were stripped or partially stripped (jamming). Luckilly, there is Big-Sert tool - I replaced all 20 of them.

The unskimmed head height is 131.00 mm (from the head face to the surface where the cam cover gasket sits).

By the way, I had a 1973 Triumph Stag for 21 years, sold some 5 years ago.

 

I thought I recognized the name from the TSN Registry database and TSN Phorum, of course I was President and Chairman of the TSC USA for 10 years from 2000-2009, ran the Triumph Trans AmeriCan Charity Drive in 2009, during that time and after I also I ran TriumphStag DOT net until Krusty MotorSports servers crashed, now I am trying to find a volunteer to get it back up and running.

Working on Stag #4, got a customer wanting his 2997 OE Stag engine rebuilt to my standards, - that is until my XJ8 decided to have issues.

Time to go make a coolant mess in the garage draining the AJ27 block ...

 

Okay, I finally got the crank bolt, Harmonic balancer pulley (used starter method quickly, safely) and timing cover off. Yes, all guides plastic cracked and the gold colored guides are metal with plastic covering.
I'll post some photos tomorrow of the timing chain guides and tensioners for archival.
Tomorrow, heads ...

 

Yep, Guides and Secondary tensioners were cracked, no surprises there. Primaries were not cracked at all on either side. The text says "... not known if these were ever replaced and they look like they are original."



I am wondering if these AJ27 engines were ever designed to last more than over 100k miles ... There is some wear in the front cam journals, I'll plastigage them to see how bad it is. It should be interesting to see if this engine has piston sleeves as indicated in the JTIS and Engine training manual.

Now to go get a better 13 mm 6 point heavy wall SureGrip socket for the headbolts, I split my other one ...

 

I guess you see some "lines" on the front cam journals. I wouldn't worry about those if they have very small height. There will be corresponding "valleys" in the front cam bearings which you can feel with your nail. It appears "normal" that the front cam journals show this kind of surface deformation which is due to the extra load on them by the chains. My 75k miles cams had similar wear and I installed them in different (36k miles) heads. I tested the cams bolted on the "new" heads without valves and they were spinning nice and smooth and now, after the rebuild, I also have very quiet valve gear.

The first steel-lined AJ-V8 came off the production line in the year 2000 on August 18th at 10.43am having the engine number 00 08 18 1043 so if your engine number is higher than this, you will certainly have steel liners.

 

Stagby, the deterioration looks to be standard for a vehicle with your mileage and everything appears to be original. While it doesn't indicate that catastrophic disaster was imminent your replacement of these parts is timely.

I'm sure you have already read this in the repair manual, but even though they are keyed, the two crank timing gears can go on backwards, to avoid this they have timing punch marks which should be visible to the assembler (i.e. face towards the front of the car) and the second check is that the two gears should be staggered to each other by 1/2 a tooth.


.

 

I took a 13mm impact socket and ground the outside down until it would fit in the head. You can get an inexpensive set at harbor freight.

 

Before I saw your post I rounded two head bolts using the 6 point 13mm impact socket and 18"breaker bar.

After getting that sinking feeling and feeling really pissed off, I stopped, used the new 6 point 1/2"drive 13mm socket and the rest successfully broke lose with an 18" breaker bar.

To remove the rounded ones, Harbor Freight has an Extractor Socket Set for $19.95 minus your 20% coupon make them about $16 a set. These are the only Socket Extractors I have found to fit down the 21.75mm head bolt hole in the head.

CAVEAT of these Pittsburgh Tool Socket Extractors is, NEVER EVER reverse the Extractor Socket on the bolt head after it bites into the bolt or nut or you destroy the Extractor socket jaws, they are unidirectional in the loosen direction ONLY, tighten direction will round out the extractor jaws against the hardened bolt. Good news is, you just take it back to Harbor Freight and get another set for free.

Top Bolt is a good one, Middle and bottom are rounded - extracted with the Extractor socket. Top two sockets are Craftsman 6 point one regular, one Impact deep reach, I recommend 1/2"drive, but the Extractor Sockets are 3/8"drive.




Anyone use the Lincoln LS 3.9 head gasket set with head bolts?