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Busso: a question of timing?

14K views 62 replies 9 participants last post by  JeremyG 
#1 ·
Today I checked the timing on my Busso 3.0. The results looked pretty bad - interested to know what others think.

It's in a recently-acquired GTV that has not run for several years; the guy I bought it from was in the trade and mentioned his mechanic had changed the cambelt at some point. The belt itself looks to be in good condition, and has evidently not been "wandering" on the sprockets.

When I removed the cambelt cover I discovered red paint blobs on the cover and on one of the cam sprockets - that didn't exactly fill me with confidence that cam locks had been used previously.

From the pics below you can see that the inlet cam on the rear bank is timed about right; but the other three are out, with both cams on the front bank out by some margin.

So a couple of questions:

1) How badly would this have affected the engine's running?

2) I need some longer bolts for the cam locks. Can anyone confirm what size they are - they look like M8 standard pitch?

(I've tried the bolts I have for my Twin Spark cam locks but obviously they are a different size... )

Pics below show paint blobs on the inlet cam, rear bank; then the locks on both cams on the rear bank; then the inlet cam on the front bank; and finally the exhaust cam on the front bank.
 

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#3 ·
These are the LaserTools cam locks for the Busso V6 - which quotes the correct engine code for my car...?

If you look at the first pic, the cam lock fits the lobe on the rear inlet cam spot on. What makes you say the lobe shape is different (not a criticism - just curious)?
 
#4 ·
just a quick question. when i do the3.2 the locks all sit on different lobes not all on the front lobes .. so maybe they also need to be on different lobes too

if i recall i changed the supplied bolts m8 x 1.25 pitch.. for either 40mm or if they were 40mm for 45mm .. also bolts wont hold cams still just for location need a pin wrench to hold pulley still while torquing up

https://www.totallyalfa.com/shop/tools/v6-camblock-fixings/ bolts

https://www.totallyalfa.com/shop/to...4v-12v-and-twinspark-exhaust-cam-pulley-tool/

and a dial gauge for checking tdc too cheapest on ebay

https://www.totallyalfa.com/shop/tools/tdc-gauge-holder/

https://www.totallyalfa.com/shop/tools/v6-crankshaft-nut-socket/

https://www.totallyalfa.com/shop/tools/v6-busso-engine-cam-belt-tensioner-adjustment-tool/
 
#6 ·
Back two cam locks sit on the lobes closest to the belt. Front bank inlet cam - lobe closest to gearbox, front bank exhaust cam - lobe closest to timing belt. Its just the front bank inlet which is the odd one out.

You can crack off the sprocket bolts and turn the cams one by one until they are all correctly positioned, at this point I'd just doublecheck the tension is OK, re-tension if necessary and then tighten the sprocket bolts again. The hardest bit will be freeing the sprockets from the tapers if the belt is going to be left on.

It's going to run a million times better with the cams timed properly, whoever did it before was clearly a bit of a nugget. I'm not sure how much faith I'd have in the belt, tensioner, idlers for the long term but if you're justing wanting to see if it can run better then there's no harm in retiming it with the belt left on for now.
 
#8 ·
You can give that a lot of help without much effort. I suspect the poor lobe fit is because of the camera angle, but they must fit snugly. If they don’t, then send the locks back.

Here’s what I’d do:

1) Make damn sure I had TDC. I assume you’ve taken the dial gauge out in one of the pics? You definitely need a dial gauge.
2) Loosen the sprockets on the front two cams - 25mm spanner on the flats, 19 on the sprocket bolt. Loosen them one turn max.
3) With a (preferably brass) drift, tap the sprockets off the taper though the window in the cam cover.
4) Using the locks, get the timing spot on for the front two, lock up the pulleys again.
5) Rotate the engine a few times and check timing.
6) At this point, the only one that should be out is the inlet of the rear bank.
7) You may be able to fix the rear one with the same loosening approach - a suitable small pry bar behind the sprocket can spring it free.

You don’t need the long bolts right now - get the cam in precisely the right place using the flats on the shaft (so that the lock is dropped on fully) and nip up the pulley with your other hand.

Agree that it will run a shed load better - the idle on that must have been catastrophically bad.
 
#9 ·
Thanks all for your comments - very helpful.

The belt is still in place and tensioned; my plan was to release the cam sprockets and nudge each cam into place as per Pud237 (Dan?) and rxe's advice above.

I've successfully loosened all of the sprocket retaining screws; but so far the sprockets are refusing to budge. I've applied WD-40 and will try again tomorrow.

Question: are the sprockets more likely to come free with the belt de-tensioned?

In the long run, if the motor is serviceable I will absolutely be replacing the belt, idlers and tensioner, but right now I'm trying to assess its condition without throwing too much money at it. The belt itself looks good so I'm happy for it to stay put at this stage.

Couple of other updates:

- Don't worry, I'm using a dial gauge to identify TDC on cylinder 1; I'd removed it at the time I took the pics.
- Bolts for the cam locks are M8 std thread; I bought some 50mm bolts from my local tool shop which are probably a whisker long - therefore, 45mm is a good shout.
 
#10 ·
You do not have to take off the belt to loosen the sprockets. The front two will come off easily with a tap through the window. The back two will come off with a sharp tap with a pry bar underneath them. The rear one is very hard to get off with the belt still in place, you really need the rear bank intake off unless you have made a custom pry bar....

Edit - they’re not like the 12v sprockets with a key way. They’re a taper fit, WD-40 not needed, just a sharp tap.
 
#15 ·
OK, still not starting (having fixed the timing). I’m pretty sure I have sticking valves, resulting in zero compression on 4 cylinders.

Now, I’m sure the best way to fix this would be to remove and overhaul the heads - but before I take this step, is there any way to un-stick the valves without removing the heads?

For example - if I remove the camshafts and cam followers, will I get enough access to the valves stems to work them free?

Or is that wishful thinking?
 
#16 ·
can you not do a cylinder leakage test to confirm before going further ... you could try freeing valves with penetrating oils etc but if they have been stuck open the seats could be damaged or the valves bent if it snapped and someone fitted a belt in hope..
compression test would do but cylinder leakage better and diagnosing leaks.. or a small camera to look inside cylinder cheap on ebay
,,
 
#17 ·
If a valve is sticking, it should be really obvious - look for cam buckets that are clear of the cam when the lobe is pointing away. If you have any material clearance, then the valve is stuck. With the lobe pointing away from the bucket, it should be free to spin. The buckets themselves might be corroded (??? unlikely) but then stuck valves are pretty unlikely.

If all the buckets are free, and there is no clearance, you probably have bent valves. Those cams were miles out in the earlier picture. I suspect that was why it was laid up?
 
#19 ·
He already reported that it has 0 compression on 4 cyllinder I believe. Busted bottom end would not show 0 compression only if it is a hole in the piston which I doubt. I am pretty positive that the engine had broken or slipped on the time belt and bent the valves. I would suggest to get a set of second hand heads in good condition. These go in my country for 200 to 400 euros if it is a 2.5 or 3.0. However, to confirm, do a leakdown test or remove the heads.
 
#20 ·
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!)
 
#21 ·
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.).
 
#22 ·
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!
 
#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?
 
#26 ·
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!
 
#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.

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930589

930590

930591
 
#29 ·
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.
 
#32 ·
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??
 
#33 ·
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.
 
#38 ·
I did the heads in situ on the GT and can confirm the utter ball ache nature of the whole process. Drop the engine, much easier, do the belt and check the clutch at the same time. And fit an LSD.

I changed the big end shells on the GT mainly for piece of mind. The shells weren’t expensive, and it was about an afternoon’s work.
 
#39 ·
I did the heads in situ on the GT and can confirm the utter ball ache nature of the whole process. Drop the engine, much easier, do the belt and check the clutch at the same time. And fit an LSD.
I take your point, but to be honest my main objective in buying this car (aside from the fact I’ve always fancied a 3.0 GTV) was to get to know the engine - plus, having not driven it yet I don’t know what else may or may not need doing on this car. So right now I’m going to do enough to get it driveable, so I can then assess it and decide if it’s worth keeping. And it will surely be easier to sell on as a runner, if that’s the decision...

So, turns out the front head will come off with the engine in the car - following removal of the cooling fans, exhaust manifold and power steering pump. I also removed the o/s engine mount to raise the engine a little; raising or lowering helps remove various components on the front of the engine.

Anyway, the front head is now off and is probably in worse condition than the rear head - with 5 out of the 6 inlet valves bent. Given the extent of the damage my plan is to go with the second hand heads I’ve been offered, have them pressure tested and skimmed, then fit them with a new head gasket set but use the same cambelt, tensioner and water pump for now.

Given the access I currently have I’ve also removed the alternator and starter motor which will go off for testing; I’ll also replace oil and oil filter plus o/s inboard CV joint boot (which is in two pieces)... I’ll also replace the top hat bushes on the gearchange whilst the engine bay is relatively empty.

Once it’s back together again, I’ll do the cambelt change if the rest of the car checks out.

So - I feel I’ve made progress - at least I’ve finished the dismantling phase...

Pics below of the block with both heads off, plus the very badly bent inlet valve on cylinder 6.

931083
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#40 ·
Never refit a used belt...not worth the risk compared to the cost. If you really must do it...make absolutely certain you refit it running the same way it came off. Refitting it so it runs the opposite way is a sure way to a load more bent valves!
 
#42 ·
Yes, all done now. As I was leaving Homebase last week having picked up a pressure washer, I spotted this electric drill press at the knock-down price of £29.67!!!

It's a bit agricultural, but it made light work of drilling holes through a piece of steel bar I had left over from a repair to the boot lock mount on my 166 a few months ago:

931303


Add some lengths of 15mm copper pipe and the liners are now clamped down:

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The alternator and starter motor are currently at the repair shop, and I'm due to collect the replacement heads on Monday.
 
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