3.0 Help Please

[V AR 164]

Valve stem seals do not affect compression. Their only job is to stop oil seeping down the valve stem into the cylinder. The valve head on it's seat is what seals the combustion chamber.

Ahh ok, thanks Mick for clearing that up for me.

Hi Andrew
Agree with Mick, worn valve stem seals would not give low or zero compression. With the compression test conducted using the oil and still no compression suggests bent valve or damaged valve seat.

Yeah I agree, but even then a damaged valve seat should read at least a couple psi? When I did the test, I couldn't even hear the piston trying to compress anything, it's like a valve is completely missing.

The 12V motors never spit a pushrod or chew off a cam lobe? Just asking; by looking at the valve train design I'd wondered if either was known to happen.

Not sure, although if it were a cam lobe that's sheared off, wouldn't it still have compression as the valves would be stuck closed?

Also when it initially started to misfire, there was no weird noises or anything.

Would it perhaps be a slipped cam belt?

Could also be the issue however it still drives fine on the 5 cylinders.

And yes I also know about the afm. I've discovered that when it is unplugged for the first few mins, it runs like a dog, but then it actually idles out smoothly and if your gentle on the throttle, it can actually be driven normally.

Also excuse me if I say anything silly, still learning!

Cheers, Andrew.

[four90s]

Hi Andrew,

Yes they do wear cam lobes out. It took me ages to work it out when I had an issue (also in a 164 12v).

Would only run on 5 and the inlet for that cylinder got hot.

Swapped injectors and ignitions and checked fuel flow and and...

Finally bit the bullet and took the cam cover off (the rear one of course) and I had about 4mm clearance on the exhaust valve. The inlet was fine.

Swapped a cam from a 2.5 parts motor and all good. Had to swap out the bucket as well, as the top of that was severely scalloped. Didn't change anything else.

Cheers
Steve
Adelaide

[V AR 164]

Hi Steve,

Thanks for the info, I need to replace the valve cover gaskets anyway so I'll take them off tomorrow and have a look.

If it is the cam that's bad, can it be reprofiled or regrinded? Reason being is that I believe these cams are aftermarket as the car has a lumpy idle that I have not ever heard in another 164Q, and I wouldn't replace them with standard Q cams.

Cheers, Andrew.

[Mick A]

The V6 does sometimes break exhaust valve rockers, but not usually on 164's as they are reinforced and stronger.

I'd say you've probably burnt out a valve, that's just an educated guess, but of course without seeing it, it's just a guess! Looking forward to hearing what you find to be the problem.

Mick.

[four90s]

I should have added that I tested compressions as well and they were all good and roughly the same, as it was only the exhaust lobe that failed.

Good luck with the cam if it's an aftermarket one. You might be able to get it built up and then re-ground. I know of places here that do that sort of thing, so there must be similar shops in Melbourne. Maybe talk to Vin Sharp

When cams fail it's usually (in my experience) a little bit of something that scores the wear face on the cam and eventually the case hardening wears through. Once that happens the remaining non case hardened material wears rapidly against the other surface and time to find another cam.

I did a few when I worked on Mercedes. Had a six cylinder SOHC one once I think had all lobes with wear. Not sure how it still ran.

Steve
Adelaide

[V AR 164]

Steve, you may be onto something.

Just drove it into the garage and opened the bonnet. Felt the chrome intake runner on the missfiring cylinder and it was definitely much hotter than all the other runners.

About to take everything apart, I'll report back within a few hours. Also, what should I be looking for when I take the valve cover off? Do I need to check camshaft clearances or will it be pretty obvious if something isn't right?

If all checks out ok with the cam, I agree with Mick that it's probably a burnt valve.

Thanks alot guys!
Andrew.

[V AR 164]

Figured it out,

It is indeed a burnt valve. I took off the intake runner to cylinder no.2 and luckily the intake valve was open. This allowed for me to put the usb camera in there and found out the exhaust valve had been burnt away right next to the spark plug.

Going to get my mechanic to take the heads off and send them away to get properly restored. Won't be a cheap fix but I want to fix it completely and not just replace one valve and hope the others will survive.

While I'm at it, it's gonna get all new gaskets from the head up.

Attached are some pictures, at least it wasn't the rings!!!









Cheers, Andrew.

[bteoh]

Hi Andrew,
Glad you found the problem. Are you going to pull the heads off with engine in-situ to change the valve or remove the engine altogether and do a rebuild?
I am trying to figure out what to do with my other 164 that has broken a timing belt. Remove the heads and fix it with engine in or remove the whole engine and do a rebuild?
Let us know your progress and hope you get it back on the road soon.

[bonno]

Hi Andrew
Due to the need to pull off the head to do the job, my recommendation is to recondition both heads now if you plan on retaining the car. Quite a difference in price depending on what you want done, but will be the most economical option in the long term, than just to replace burnt valve. But on the other hand if you want versus the need to carry out a complete engine rebuild then that is another story and this depends on what the budget will allow, will be the deciding factor.

[V AR 164]

Hi bteoh,

Not sure but I really don't want the motor to come out. As Citroenbender said, it would disturb too much. However, if your motor has bent valves, maybe the crankshaft could be out of balance and the big end bearings out of round? I would take the motor out and get everything checked over, but the cost would be a lot. Maybe you could look at a second hand motor and simply do a straight swap. 164's are cheap enough now to consider this option.

I am very tempted to attempt this job myself, but am put off by what can go wrong if I don't get something right. I would love to learn as I have all the necessary manuals and pdf's, but there is just something telling me not to do it.

Has anyone done a head gasket on a 3ltr and is it that difficult? Any tips and tricks?

Bonno, yes I am wanting to get both heads reconditioned at the minimum. If I'm going through all this trouble, might as well do it properly. Budget is definitely something I need to consider, which is another reason why I want to do it myself. If I can minimise labour costs, I then could possibly squeeze to get the heads reconditioned.

Cheers, Andrew.

[bteoh]

Andrew quoted :-
"Not sure but I really don't want the motor to come out. As Citroenbender said, it would disturb too much. However, if your motor has bent valves, maybe the crankshaft could be out of balance and the big end bearings out of round? I would take the motor out and get everything checked over, but the cost would be a lot. Maybe you could look at a second hand motor and simply do a straight swap. 164's are cheap enough now to consider this option."

I did buy another running 164 just for this purpose and that was the original plan. Like you, I have never pulled an engine out of a 164, so wasn't sure how difficult a job it might be. On the Alfa Bulletin Board in the US, some members have apparently said it isn't too difficult .........

Hope yours gets sorted soon.....

[Citroënbender]

I'd only advocate a "topical" or "spot repair" on a simple, accessible motor. The sheer effort and expense of what is necessary whether one services a single valve or a whole bank, is my reason for that idea.

Either way, I'd assume liner clamps are good practice and these are something else to make early in the piece or borrow a set of.

[Citroënbender]

I made small triangles with a hole in the centre for a head bolt/stud and a dab of MIG to create a "half dome" approx. 3-5mm across on each corner. Two of the corners press on adjacent liner edges and the third registers on the deck between bores. At the ends, one half dome out of the three isn't used.  Depending on the head fixing, the holding bolt or stud length is taken up by a cut length of 20×20 SHS pushing onto the triangular plate.

[V AR 164]

Thanks guys, really appreciate the support.

Just cracked open my workshop manuals and it doesn't seem too difficult. The main thing I'm nervous about is the timing of the motor. I'm assuming you set it to TDC with all cam marks and flywheel marks lining up?

I have also read about those clamps. I've saw someone made a set out of pvc pipe and big washers, and I would plan to do the same.

So essentially is this the very simplified rundown?
-Make sure it's at TDC
-Remove plenum and valve covers
-Double check timing
-Remove timing belt
-Remove cam 'caps'
-Take off cam gears
-Remove cams
-Crack loose head nuts
-Remove nuts
-Lift off the head
-Use the compressors on the liners to stop linear movement of liners and compromising seals

Pretty much it?

I would more than likely send the heads away to be refreshed completely, just to make sure it doesn't happen again anytime soon. Even if it costs a pretty penny, I think it's worth it.

Bteoh, I have a complete workshop manual showing every step needed to remove the engine, if you want I can send you pictures of the pages to your email.

Regarding removing the heads with the engine in the car, it is possible yeah? Of course the burnt valve is on the rear bank of cylinders. Hopefully I won't need to drop the motor.

Cheers, Andrew.

[bteoh]

Hi Andrew,
Thanks for the offer but I do have a copy of the car disc for the 164. I am still toying with the idea of removing the heads to see the extent of damage. I presume you have to remove the false firewall to gain more access to the rear bank of cylinders?
I shall follow the progress of yours and see how it goes.
Cheers