Loose valve tappet guide or?

[lowact]

Um, pls can I have prognosis?
Intended to head off tomorrow on a 1500 km round trip. But the clatter that I had always attributed to a loose tappet guide, which would go away after a while, doesn't go away anymore. And now its got worse and I seem to have lost most of my vacuum. The attached are little videos, engine sound track and view of vacuum gauge. Two questions, am i correct about the tappet guide and will I make it home?

https://1drv.ms/v/s!AiSPBKa26IcchMMflesT0bzfG0PZEw

https://1drv.ms/v/s!AiSPBKa26IcchMMgiQ807gcGwXjxzA

[AussieEtype]

I certainly agree it could be tappets but it does sound more like a vacuum leak or even an exhaust manifold leak.

Sorry I cannot be more helpful.

Garry

PS where you going, I didn't appreciate that your car was actually on the road?

[lowact]

Down to Gippsland. Is a regular trip. Car is (has been) well and truly on the road, I've been talking about taking it off the road for years. 2019 is looking likely. Here is another vid, shows what happens when I remove vacuum. I've titled it "why I hate carbs".
https://1drv.ms/v/s!AiSPBKa26IcchMMjKeRWaeTS-KOwrw

[abowie]

First step for ANY top end noise on an E Type.

TIGHTEN THE TIMING CHAIN PROPERLY.

So many times...

[lowact]

If it's timing chain, to fix would require complete strip-down heads off, sump off ? Meanwhile I wonder, why might I have oil in the bottom of my inlets?

[vee12eman]

Hi.

Oil in inlet could well be from overfilled dashpot reservoirs. Should not do any harm, but probably best avoided in future.

Regards,

Simon

[lowact]

Also seems to be a bit sooty in the inlet manifolds, is there a clever procedure for checking valve timing with just the timing covers removed?

[Ole-xke1974]

By timing covers, do you mean the valve covers ?
If so, when the crank is at the TDC for cylinder 1, your two cams should be able to accept the timing setting tool on both cams like shown in the picture.
If the notches are off center and the tool is unable to be fitted, you may have a problem.
Remember only to turn the engine CW (standing in front of the car looking at the engine) to avoid the tension on the cam chain to be on the chain tensioner.

[MarekH]

Meanwhile I wonder, why might I have oil in the bottom of my inlets?

That is probably petrol. It takes a lot of fuel to start a carburettored v12 and the heavier fractions of fuel which don't end up in the cylinders will condense on the walls of the manifold. Unless the car has fully warmed up, enough to burn off this excess, then this will just roll down and collect in the base of the water jacket and still be there after the car is shut down. (The more complicated fuel injection algorithms include terms for the amount of fuel condensing onto the walls and the amount of fuel evaporating off of the manifold walls at different temperatures.)

kind regards
Marek

[PeterCrespin]

Marek is right and it’s one of the reasons the manifolds are heated.

As for the thread title, I will personally rebuild for free anybody’s Jaguar V12 that has suffered a loose tappet guide.

[lowact]

Thanks gents, I hadn't thought of thick petrol, seems likely when u look at it closely. And yes Peter, yr wager would be safe, apologies. Timing covers, valve guides, tappet clearances.
Current status of of the open-heart surgery:


Bad news, everything seems good, nothing that might cause the noise or thr weak idle vacuum. No signs of wear, chain tensioner looks luvely, dampers appear all in place, chain is firm, no noises or catching when I turn by hand, tappet clearances all more than 10 thou and less than 13 (bit tight but ok?), Inlet valve guides have no sign of having moved (squinting down the port and poking with screwdriver), jack shaft bearings good, no runout. Also valve timing seems spot on, don't have that C3993 tool (yet) Ole, so I'm measuring (vernier).


Anything else I might check (that doesn't involve removing the cams)? Noise was seemingly from front of B bank. Exhaust valve guides, how to check? A loose exhaust valve guide wouldn't cause weak idle vacuum? Or am I looking in the wrong place? I am really not wanting to remove the cams at this time, currently favoring puttig it all back together and hoping I was imagining it :-(

[PeterCrespin]

Compression test would be relevant to ring pack and piston condition. I just checked my V12 the other day. Most at 130, couple nearer 125 one at 135 (low comp American spec and throttles jammed only part open).

[MarekH]

First step for ANY top end noise on an E Type.

TIGHTEN THE TIMING CHAIN PROPERLY.

So many times...

There isn't anything to do (either properly or otherwise) on a v12, Andrew. The timing chain damper is either broken or it is not. If it is, then there will be a lot of noise as you come off of the power, but otherwise it may seem mostly ok. The chain may well be reasonably tight when at rest, since the spring will still do its job. Appended is a picture of a broken timing chain damper and a new replacement unit.

smtenP1010003.JPG (98.95 KiB) Viewed 11757 times

I also append pictures of the old timing chain and a new timing chain which was subsequently rolled round. Note how much wear there is on the old one, such that it fouls one of the screws as shown at the white arrow. This will have made some noise and worn metal will have found its way into the oil. The same (new) tensioner is in both pictures.

smoldchain.jpg (172.66 KiB) Viewed 11757 times

smnewchain.jpg (188.55 KiB) Viewed 11757 times

So if you can, assuming the damper is not broken, check to see whether you have daylight between the chain and bolt at the white arrow.

This much chain wear, or breakage like this, will also substantially add to the wear on the slipper plates which guide the chain.

kind regards
Marek

[PeterCrespin]

Compression test would be relevant to ring pack and piston condition. I just checked my V12 the other day. Most at 130, couple nearer 125 one at 135 (low comp American spec and throttles jammed only part open).

[abowie]

There isn't anything to do (either properly or otherwise) on a v12, Andrew.
kind regards
Marek
[/quote]

Thanks for that Marek. I view the forum by new posts and don't always notice when it's a S3 post.

We have had two 6 cylinder cars brought to us recently for investigation of engine noises after dire predictions from third parties. On both occasions tightening the upper chain solved the problem.

[Ole-xke1974]

Marek,
it looks like you replaced the timing chain tensioner without taking the heads off. Have you been able to seal the heads without leaks after that ?

Thanks ........ Ole

[lowact]

Thanks Marek, I also noted you've removed the timing cover with the heads on, I read (Kirby Palm) that this is possible by destroying the studs connecting the head to the timing cover … so I am looking down from the top. I appear to have comfortable gap between the chain and the bolts that attach the sprocket retaining bracket.

Peter, my compressions seem ok, 9.8 – 10.5 Bar (142 – 152 PSI). This is with US spec, 9:1 compression, my understanding is that the 1st letter of the engine no. suffix denotes the compression, low, std, high, L=7.8:1, S=9:1, H=10:1 (or higher).

I am thinking the evidence supports a loose exhaust valve guide:
1. Everything else is eliminated
2. The noise is cyclic, slower than rpm,
3. Stethoscope suggests the front of B bank
4. There is acrid smoke when cold, this could be by oil being pumped by sliding valve guide, into the exhaust port, oil seal would not be effective if the guide is sliding
5. The noise used to stop when the engine warmed up, which could be due to the guide expanding and seizing in the head
It is because the noise is now not stopping that I'm thinking I can't ignore it any longer …

Here is pic looking down the inlet port:


The guides protrude, do we know if this is normal? Also imo it looks ghastly for an inlet port, do we know if this is typical?

Thanks, I'm appreciating this.

[MarekH]

Dear Colin,

It is perfectly normal for the valve stem guides to protrude. The only things they can do is become oval through excessive uneven wear or cracked when someone did a botched replacement and used a hammer on them rather than reaming out the hole and pressing in a new one. Not to be confused with valve seats.

Perhaps Kirby needs to know that the six studs on the front of the heads can be loosened and raised far enough to remove the timing cover by using the double nut method on them. (He hasn't owned an xjs for years.)

If the valve timing clearances are within spec and unchanged, then it suggests that the relevant valve seat ought not to have moved, or rather if one has moved, it is inconveniently back where it started just now. That doesn't mean it isn't capable of dropping, which I presume is what you are worried about, even though you are talking about valve guides.

As my computer doesn't really do sounds or moving pictures, I haven't viewed the videos, so I am limited to suggesting what is easy to diagnose given the level of stripdown.


Dear Ole,

With the cam covers off, you have all of the access you need to reseal the top end with the timing cover off. The tricky bit is that the sump gasket would be more likely to leak as it'd likely tear as the front of the sump is lowered a tad. The person I did this for was happy with it, so I presume it was no worse than the oil covered mess that it was before.

kind regards
Marek

[PeterCrespin]

I am thinking the evidence supports a loose exhaust valve guide:

4. There is acrid smoke when cold, this could be by oil being pumped by sliding valve guide, into the exhaust port, oil seal would not be effective
The guides protrude, do we know if this is normal?

Thanks, I'm appreciating this.

The guides cannot slide - that’s why they have circlips and a close-fitting steel spring seat: to prevent dropping and rising respectively. And since all guides will look the same in the other ports you can be sure their position is normal.

[lowact]

Thx I was assuming based on the "loose valve guides" cause of the matching symptoms in my "how to read a vacuum gauge" guide. So now I suspect either valves loose in their guides or failed valve stem seals, the latter is logical, everything else plastic or rubber has had to be renewed, valve stem seals would be no exception.
I note in the parts manual that only the inlet valves have stem seals, I wonder why not the exhaust valves also?
Meanwhile car is now back together and, while there is still the acrid smoke during starting, idling, decel'g, the noise is gone, i've done something right, dunno what...
Lunch at Lakes ...