Zel's Fleet Blog - BX, Jag XJ-S, Sinclair C5, Mercedes 208D & 230TE, AC Model 70.

[MattBLancs]

Very annoying timing!
Had similar with my 1st car (MK2 Golf) bought a replacement (306 1.9 TD) and the golf promptly sprang a leak on the water pump whilst just sat on the drive!

(Thankfully is separate from timing belt on those, but annoying working on something you'll get no benefit from!)

Does the Caddy not have enough "VW scene" following there's folks queuing up to drop 1.8 T or VR6 or whatever silly engines in place of the SDi ?

[CitroJim]

Oh dear Zel, hope it's noting serious with the Caddy...

[Zelandeth]

Starting point today:



Ish. That's a photo from a week or two back, but you get the idea.

Couple of hours and a small amount of swearing (mostly at the bracket the throttle linkage/kick down cable attach to) later...





Note that some of the intake manifold bolts are different, so keep them in the order they came out.



The choke cable end is really frayed so definitely wouldn't be going back into the linkage on the carb if I took it out, which is why the one carb is just tucked in the corner. There's plenty of length of cable available to keep it out the way so I figured I'd just leave it alone rather than adding to my immediate to do list - though the cable does want changing longer term.

Can't really see anything useful looking down towards our offending valve.



At least not that I'm able to interpret.

It's not something obvious like a bit of rag having got sucked into the intake anyway, so the head will have to come off to investigate and resolve whatever is going on.

That will be the next step. I'm not touching the exhaust manifold bolts, the join to the downpipe has clearly been apart relatively recently (the bolt is still shiny) so it will be getting split there.

I was really quite surprised with how clean things were under the intake gasket/valley cover given that these engines don't exactly have a reputation for internal cleanliness.



Again kind of wishing I knew better what the story of this car was. I almost wonder looking at this whether this engine has had at least some rebuild work done (the water pump and timing cover gaskets externally look bright enough to be essentially new), and it then just sat around for a long time before developing this problem when fired up eventually. I did note when it was running that there was very little apparent blow by.

Nothing really found yet, aside from a surprisingly clean looking engine anyway. We'll know more when the head comes off.

[MattBLancs]

Those manifold bolts look to have tales to tell: one with a slot cut on its head and the other with a bonus extra penny washer!

I too like the "stabbed cardboard" technique, though I'd have a very obvious "FRONT" label as pretty confident I could have it 180° wrong on reassembly. Unless you have a "top of Halfords box = front of car" rule in place

Does look very clean in that valley.

Only thing I can't be sure about is the sort of "orange coloured ring" seen down that valve port. Otherwise looks pretty normal to me.

Follow with interest as to what you come across, it's a puzzle

[MattBLancs]

This bit:

Orange ring

[Zelandeth]

Those manifold bolts look to have tales to tell: one with a slot cut on its head and the other with a bonus extra penny washer!

I too like the "stabbed cardboard" technique, though I'd have a very obvious "FRONT" label as pretty confident I could have it 180° wrong on reassembly. Unless you have a "top of Halfords box = front of car" rule in place

Does look very clean in that valley.

Only thing I can't be sure about is the sort of "orange coloured ring" seen down that valve port. Otherwise looks pretty normal to me.

Follow with interest as to what you come across, it's a puzzle

The ring of rust is indeed what has me curious. It may be as simple as rust on the valve seat if that cylinder has got wet (I'm assuming the valve seat inserts are steel). Guess we'll see.

The orientation of the box is that the tab sticking out the top of the box is the bonnet of the car. It made sense to my brain.

The bolt with the slot in is odd as the heads of all the bolts, including that one are in fine shape. So I really don't know why someone did that. The additional washer on the one is on the only one which sits in a slot rather than through hole. Uncertain if that one would originally have had a larger washer on than the others.

[Zelandeth]

Literally only had 15 minutes for it today, but was determined to make some progress however small.



Rocker shaft and push rods removed. I also pulled three cam followers at random for inspection. They all look like this.



The mark around six o'clock is a fingerprint, not surface damage. Feels completely smooth to the touch.

Next I need to remove this engine steady...



Which I note is already missing a bolt. The equivalent bracket at the rear is what the throttle linkage and kick down cables fasten on to, it can stay where it is as everything else is already detached from it. Which caused much swearing as I had to unscrew the adjuster for said kickdown cable and the adjuster was seized.

Then either split the downpipe or exhaust manifold.



I was leaning more towards splitting the downpipe from manifold but I'm now second guessing myself. I can see that join being a git to re-seal afterwards, and from the looks of the gasket, the manifold has seen about as much service since the engine was apart as the innards suggest, so I may end up pulling the manifold instead. Aside from anything else I have new gaskets for that I don't for the downpipe... manifold is several orders of magnitude less annoying to get to anyway.

Elsewhere, apparently I do have at least one water ingress issue to trace.





I really hope that's not a sign of rot in the screen surround hidden under the chrome covers...

[Zelandeth]

Off with its head!





Nothing immediately obvious like a seat hanging half out the head, though I'm going to do a leak down test on all of these later today to see how well (or not) the rest are sealing.

Can't pull the valve yet because I realised that I lent my valve spring compressor to someone about 15 years ago and never saw it again. Have one arriving tomorrow.

Here's a closer look at number 5.



Then it's neighbour number 7 which I know was firing just fine.



It does look like the intake valve on 5 isn't seated quite as deeply as on 7. We'll get a better look when I pull the valve.

There's a bit of tarnishing in the cylinder, but I've seen (and run) worse.



I am slightly suspicious as to whether this gasket had sealed properly.



Especially around here.



Just surprised to see that much surface oxidation given it's something meant to be clean, then sandwiched up against a gasket...unless whoever put it together last time just chucked it together without cleaning anything.

I did notice what appears to be a 2019 date code.



Which if it is indeed a date code suggests someone has been in here relatively recently. Which probably explains why the exhaust manifold just unbolted without any hint of protest.

Speaking of gaskets, there will be a slight delay before things go back together (obviously investigation of my issue and cleaning will take a bit of time anyway). Spot the deliberate mistake.



Yeah... someone managed to order gaskets for a two rather than three row head...despite checking three times. I do despair at my mental capacity sometimes.

[mickthemaverick]

Looking at that Zel the inlet on Number 5 looks like it may have a bent stem to me as it does not appear to be laying square to the port. It will be interesting to see when you pull it out! I agree the gasket is definitely in the dubious category and may well have been leaking, maybe related to valve damage.

[Zelandeth]

Leak test actually didn't reveal much. Which made me even more suspicious.

There is always some pressure against the valves because of the spring in the hydraulic tappets providing some pre load. So it's possible that if a valve wasn't seating 100% with that bit of pressure present, it might be without it - if for instance we had a slightly bent valve or something like that working against us.

With the valves pulled from number 5, no signs of damage to the seats at least. Things have just had a really quick wipe down with a rag here.

Inlet valve seat.



Exhaust valve seat.



Quite a bit of crusty carbon buildup around the exhaust valve seat, the valve looking correspondingly crusty.



Intake valve really didn't look bad.



Of course today is the day I've run out of brake clean isn't it...

Rolling both valves on a flat surface I couldn't see any visible wobble of the heads, so if there is anything amiss with them in terms of being bent it's really subtle.

After only a few seconds of lapping the intake was looking way better. Reckon that will clean up just fine.



The exhaust valve is a slightly different story. There's quite a lot of pitting around the sealing surface, which in a couple of places does span the full contact area.



After a little while I noted that it looks like when spinning the valve in the head that the valve head on this one is rotating a *tiny* fraction off concentric...so maybe the stem is slightly bent.

It's barely, barely visible...but my understanding on things like this is that it's perfect or it's not pretty much. Sadly I don't have the equipment to really measure the run out and see if it's just the outer part of the head that's off rather than the actual sealing surface...but for the sake of £8 or thereabouts for a valve, I'm just replacing it as a precaution. If there's any suggestion that the valve may have been subject to trauma I'd rather just change it than have the head drop off in 500 miles and write off the piston and cylinder liner...which would cost far more than £8 to sort.

Obviously I'll need to inspect the others here to ensure there are no other valves with issues. Cue potential for things to snowball...do I just replace them all out of an abundance of caution? I'm already leaning towards pulling the other head given the potential evidence of this side having had things poorly prepped before fitting and possibly not been properly torqued down. Suddenly that's another £150 worth of valves added to the bill!

[CitroJim]

Looks like the exhaust valve is the culprit Zel... Definitely do them all and indeed, lift the other head... Best to whilst all is nicely accessible and you'll know all is then good...

Be interesting to see the state of the other valves in that bank...

[Gibbo2286]

That exhaust valve looks to be seated too close to the top, I wonder if it's been ground too much by a previous fitter.

[xantia_v6]

Something just clicked for me. Maybe the person who reassembled the engine did not adjust the pre-load on the tappets. If there is too much preload, I think that the tappet will not fill with oil and won't open the valve.

Maybe you can temporarily refit the head with the old gasket, just to check the tappet preload, which if the culprit would mean that you don't need to do anything to the valves?

[Zelandeth]

Something just clicked for me. Maybe the person who reassembled the engine did not adjust the pre-load on the tappets. If there is too much preload, I think that the tappet will not fill with oil and won't open the valve.

Maybe you can temporarily refit the head with the old gasket, just to check the tappet preload, which if the culprit would mean that you don't need to do anything to the valves?

The valves were definitely all opening, I had made a point of observing the operation of the valve gear with the covers off. Closing is where I had a bigger question mark.

-- -- --

Rest of the valves are now out.

1. Intake.





1 Exhaust.





3 Intake.





Couldn't help but notice the cup in the valve head is rather odd centre...3 and 7 are both like this, 1 and 5 aren't.



3 Exhaust.





Possible historical evidence of a dropped valve in the head by this valve seat? Nothing on the piston, but I'm tending to think this is the old heads dropped on a far newer/rebuilt block based on my findings so far.

Including 5 for clarity even though you've already seen these.





7 Intake.





7 Exhaust.





The exhaust valves all have quite a bit of wear on them. So I'm inclined to at least replace tbose. Also notable that the wear line on them all is really close to the lip, whereas I'd tend to expect it to be nearer the centre of the sealing face as on the intake valves.

I do note that exhaust valves are available in 33 or 34mm diameters... could someone have put 33mm valves in here when the head was set up for 34s?

I'll dig out the calipers tomorrow and measure what's in here. Most likely I'll be getting a full set, just seems sensible for long term peace of mind.

[Rp0thejester]

Is it possible to fit the wrong size valves? I would say yes definitely, especially if DIY job, some people can't even get their windscreen wiper blades in the correct size let alone a valve