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So, a quick summary:

- Last month, having received the car (GTV 3.0, not run for several years), I pulled the cam covers, visually checked the cams and applied some oil to the cams & cam followers; checked the condition of the cam belt, and ran a compression test on all cylinders. I had zero compression on cylinders 1 and 6, and healthy compression on the other four

- I then attempted to start the engine; it did start, but ran roughly and wouldn't idle. Aside from misfiring, it didn't make any strange noises - I did not hear any clattering or metal-to-metal contact. I shut down after a couple of minutes max. (We now know the valve timing was out; and with decent compression on only four cylinders it's no surprise it ran like a dog.)

- Today I ran another compression test. I now only have decent compression on cylinder 3, with zero on the other five cylinders!

- I borrowed an endoscopic camera and looked at the piston crowns - there's no obvious sign of damage to the pistons; I could see the depressions in the piston crowns for the valves, and some letters stamped into the centre of each piston crown. However - it was a cheapo camera and the screen resolution was not great, so I might have missed signs of contact between pistons and valves

- Whilst running the compression tests, I attempted to rotate the cam followers on any cam lobes that were not under load. They all rotated freely. However I noticed at least one (inlet on cylinder 6) where the two neighbouring buckets on the same cylinder were sitting at different levels, presumably meaning one of the two valves is not closing properly. Given cylinder 6 has never had any compression, this would make sense.

- Although I don't have the kit to perform a leakdown test, it seems clear that I have several valves not closing correctly. My questions are:

1) Why - are they more likely to be bent due to contact with pistons; or are they somehow just sticking due to lack of use over several years?

2) Why are more cylinders now showing no compression - and does that push us more in the direction of bent or sticking valves?

Either way - it seems further dismantling is going to be needed to get to the bottom of this...

(Sorry - that turned into a bit of an essay. If you've read this far, thanks for doing so - and if you can offer further advice on those two questions, even better!)
1) Both are a possibility, but damaged valves are much more likely. As Dan said, he never saw sticking valves on a V6 and he has done a number of them...

2) Probably the result of turning over the engine with incorrect timing. Yes.

As I said, get a set of second hand heads as changing all the valves and redoing the heads costs probably more than 2 second hand engines. Get the spare heads checked over and bench tested, skim them and install with a complete new engine sealing kit (head gaskets, main seals, water seals etc.).
 

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I suspect you are at the “heads off” stage. Check you’ve absolutely got the cam locks on right (I don’t really understand why the compressions have got worse as you’ve sorted the front bank). There are some close ups here: https://www.alfaowner.com/Forum/motoring-images/1130114-i-need-help-ive-bought-a-166-a-3.html Make sure all the lobes are in roughly the right direction, and that you’ve got the locks on facing the right way - I’ve done this, the engine turns, but doesn’t work.

If all that checks out, heads off and survey the damage. You’ve got a hole in it somewhere, hopefully it is just valves. I wouldn’t get scrap heads just yet - grinding in valves is cathartic, and you don’t know how many are broken!
 

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If all that checks out, heads off and survey the damage. You’ve got a hole in it somewhere, hopefully it is just valves. I wouldn’t get scrap heads just yet - grinding in valves is cathartic, and you don’t know how many are broken!
Of course, I suggest getting new parts after the damage has been assessed.
 

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Discussion Starter #24 (Edited)
The rear bank cam sprockets needed a fair bit of persuasion to remove them... and the purchase of a pry bar from Screwfix...

Out of interest - has anyone ever found one of the official Alfa pullers - part 1.860.954.001? If so, do they work with the engine in the car?
 

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Discussion Starter #26
Progress? :)
Some, but progress has been limited by family commitments, and rainy and now frosty weather... basically, I’ve removed the belt, top idler, cam sprockets, cams and associated brackets and covers from both banks plus the exhaust manifold fixings for the rear bank. I need to separate the rear manifold from its front pipe - one of the two nuts came off cleanly, the other one was already rounded off and is of course the inaccessible one nestling between the two front pipes... so a little more to do before I can push the exhaust manifold off the remaining studs and whip the rear head off... hoping to get this done on Saturday!
 

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Some, but progress has been limited by family commitments, and rainy and now frosty weather... basically, I’ve removed the belt, top idler, cam sprockets, cams and associated brackets and covers from both banks plus the exhaust manifold fixings for the rear bank. I need to separate the rear manifold from its front pipe - one of the two nuts came off cleanly, the other one was already rounded off and is of course the inaccessible one nestling between the two front pipes... so a little more to do before I can push the exhaust manifold off the remaining studs and whip the rear head off... hoping to get this done on Saturday!
Nice, cant wait to see what is with the engine. Just cut the exhaust bolts, not worth the hassle.
 

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Discussion Starter #28 (Edited)
OK, removed the rear head this afternoon. Below are photos of the pistons and valves.

On an initial examination, it looks like I have one obviously bent inlet valve on cylinder 1 with the second inlet valve not fully closing; cylinder 2 has both inlet valves not fully closing; cylinder 3 all good. All of the exhaust valves look OK. This fits with the symptoms of no compression on cylinders 1 or 2 and OK compression on 3.

I'll take the head down to my local engineering shop next week for a full assessment - but what are your thoughts on the condition of the piston crowns and the likelihood of damage to the bottom end of the engine?

(I'm asking because I'm OK with the cost and effort of refurbishing the heads; but any further engine work will kill this project from the time and budget POV.)

Thanks, and I really appreciate your help!

First pic below is of the head from cylinder 1, showing the bent inlet valve.

930588

930589

930590

930591
 

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OK, removed the rear head this afternoon. Below are photos of the pistons & heads.

On an initial examination, it looks like I have one obviously bent inlet valve on cylinder 1 with the second inlet valve not fully closing; cylinder 2 has both inlet valves not fully closing; cylinder 3 all good. All of the exhaust valves look OK. This fits with the symptoms of no compression on cylinders 1 or 2 and OK compression on 3.

I'll take the head down to my local engineering shop next week for a full assessment - but what are your thoughts on the condition of the piston crowns and the likelihood of damage to the bottom end of the engine?

(I'm asking because I'm OK with the cost and effort of refurbishing the heads; but any further engine work will kill this project from the time and budget POV.)

Thanks, and I really appreciate your help!

First pic below is of the head from cylinder 1, showing the bent inlet valve.

View attachment 930588
View attachment 930589
View attachment 930590
View attachment 930591
I am going to give myself the right of saying that there are no surprises there. Situation seems consistent with your data and symptoms.

Regarding the head refurbishing costs, are you sure that you are ok with that and know what it costs? A single valve in my country is over 30 GBP, multiply by 24, plus lifters and other work...second hand heads that are in good condition would be my bet, perhaps they would be even better as they are original, if you are not 100% confident of the machinist doing work on these heads.

Piston crowns seems good, not sure about the top of the pictore of piston crown on cyl 3, maybe it is just the photo. For the best advice, clean tops of pistons, and wipe the cyl walls and then take close up pictures of the crowns and crosshatching. Ususally if there is a valve hit mark on the crown it does not matter but then you have to check that the rod has not bent.
 

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Discussion Starter #30
Agreed - no real surprises here. Top of piston 3 is OK; what you see in the photo is the final bit of coolant I hadn't mopped out of the bore!
 

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I hope you are holding down those liners and haven't been turning the bottom end over with the heads off.
 

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Discussion Starter #32
I hope you are holding down those liners and haven't been turning the bottom end over with the heads off.
Absolutely - I won’t rotate the engine without clamping the liners down...

As it happens I’ve been offered a pair of heads from a matching engine that had only covered 76k. This could offer a relatively simple fix if the heads are sound - but what’s your view on potential damage to the bottom end, based on the pics above?

Also - I gather it’s possible to remove the front head with the engine still in the car only by removing bumper, slam panel, radiator and dropping the front o/s engine mount - is that correct??
 

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I wouldn't be too worried about the bottom end, they don't normally suffer any damage from cambelt snaps. How much are the heads you've been offered?

Taking heads off in situ is possible but its a ball-ache, I'd much rather drop the engine out, even if you're just dropping it onto a pallet but still leaving it in the engine bay.
 

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Discussion Starter #34 (Edited)
How much are the heads you've been offered?
I'm hoping to get them for less than £200 - they're complete including the camshafts
 

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Discussion Starter #37
Yes, if the heads look OK I'll have them pressure tested and skimmed before fitting.
 
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