Alfa Pages

[Kevin Smith]

I've had this 1989 vintage car for about just over a year now, and having covered 1000miles or so did a basic service (Oil and Filters). The engine has run very well up until early July when it began messing about. I did a compression check and found all four cylinders pretty much the same. Fiddling with the left (ns) carb temporarily remedied the rough idle and slower rev running (<2k rpm), but the problem then returned with vengance.

Eventually the engine wouldn't idle at all and the revs wouldn't stay constant when the throttle pedal was held part way down. A new set of spark plugs didn't cure the problem.

I found nothing wrong when I dismantled both carbs (Does any one have any information about setting up the idle stops / mixture screws and linkage as a start point - I've tried two turns out on the first two and eventually got the engine to run once another problem, with the fuel pump, was cured?)

I've also disconnected and blanked off the four balance tubes that feed to the crankcase breather system as it appears that the left hand (ns) carb idle setting is ineffective on both venturis and I suspect an air leak somewhere on that bank of cylinders.

I suppose it could be a blown head gasket, but there is no drop in water level, the oil isn't watery, only the usual condensation based 'mayonnaise' in the oil filler neck, and no clouds of steam from the exhaust pipe. Another thing is that I've noticed quite a large air flow out of the oil filler neck without the cap fitted.

Any thoughts anyone?

[Wizz]

Hi Kevin, welcome to the board.

I've had the same problem - non-exsistant idle. In my case it was a leaky gasket on the intake manifold. Note that I have a 1.5IE, eg. injection, so I don't know if it helps.. Anyway, it's easier to check the intake gaskets than the head gaskets.

Best of luck!
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//Wizz
Alfa 33, 1.5 IE (1992) (Series 3)... now with 1.7 IE

[Eddie W]

Hi Kevin
I suggest you do a float weight check( if you haven't already ) . The correct weight is 10gms and any thing much heavier throws the running to hell. They have a tendency to get heavier over the years. The boxer seems very tolerant of rich mixture so the problems can creep up on you quite gradually. First signs in my experience is a slowing of the idle as you sit at the lights and a slight hesitation as you accelerate. Float setting is about 6mm from memory.
Regards Eddie
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A LITTLE FURTHER A LITTLE FASTER

[Kevin Smith]

I removed the left (ns) carb again and checked the base gaskets and insulator plate, and found no problem. I decided not to remove the manifold itself as it looks as though the gasket seals the water outlet from the cylinder head and I didn't want the aggro of draining down the cooling system plus I didn't have a replacement gasket.
I checked the weight of the float in the left carb and it wasn't more than 10grammes, although it does look like it may be beginning to crack (which would allow petrol to get in and then it won't be a float - more of a 'sink'!)
I checked the float height by inverting the top cover of the carb, blowing in the petrol inlet and raising the float until air pressure escaped. The float appears to be parallel to the top cover, but at 4mm the clearance between the gasket and the closest part of the float the gap is quite a bit less than the 6mm indicated in some of the other posts on this site. (I'm pretty sure that the float level for the other carb was similar, but it was quite a while ago when I had it apart)

Having adjusted the idle speed and mixture screws the engine does now idle although not a smoothly as expected. It was driveable of sorts, but as I'd forgotten to reconnect the vacuum tube to the distributor it may not have been a fair test.
I haven't had chance to run it again (with the vacuum tube to the distributor reconnected) but I intend warming it up and doing another compression check before doing anything like removing the manifold or cylinder head.

Thanks for the advice so far.

KevinS

[sudman]

Hey there,

If yours is a hydraulic tappet model, I had an issue with similar symptoms, but the car was also dropping to 3 cylinders frequently as well. Turned out one of the lifters was badly worn, reconditioned the heads and off she went.

A long shot but it might work!

Cheers,

Richard
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Just because it's old... doesn't mean it can't go fast!

[Kevin Smith]

I've had another go at the four wheeled shed and eventually got it to run again once I'd sorted out a fuel supply problem.
Anyway, I warmed up the engine for about ten minutes and did another compression test on the cylinders. All four were between 200 and 210 psi, so I don't think there's a problem with the head gasket, pistons or valves & valve seats.
It still runs very unevenly at idle and doesn't appear to be drawing air through the left hand carburretor - the idle setting screw seems to have very little effect.
I'm guessing that the if a hydraulic lifter wasn't working its associated valve won't be opening at the right time and if it can't draw in any fuel/air mixture then that cylinder won't contribute to the engine's power output.

I don't know for sure if the engine in my Alfa has hydraulic lifters, but it would be a fair guess that it has, as it appears that the cam covers are held on by the cylinder head bolts (not ideal for manually adjusting tappets!)
Does anyone have any idea whether it's possible to remove the head from the engine in-situ as I don't have facility to drop the engine out of the vehicle because it has to stand on the road.

Can anyone answer me the following questions:
Are patent part cylinder head gaskets, from Partco or Cafco or the like, as reliable as the Genuine Alfa ones?
Are the head bolts resuable or not?
And, what is the tightening procedure and final torque setting for the head bolts?
Thanks in advance for any info.

[munro]

Hi Kevin.

Can I suggest you try the simple stuff before launching into the heavy stuff?

Replace all vacuum hoses - or closely check them for cracks/leaks etc. This stuff is usually very cheap, hardens and cracks or gets plugged up over time - so often not worth bothering with a visual check.

I would suspect an intake manifold or carb base gasket or throttle spindle leak first. This can often be detected using an aerosol can of carb spray, or brake cleaner, or really any highly flammable volatile spray. Spray all around intake manifold carbs etc. and listen for a repeatable change in engine speed...you might need an assistant to hold a high idle for this. If an air leak is present, then the added "fuel" will lift engine speed. Need to have choke off for this. Don't over do it. SAFETY NOTE: make sure you have a working fire extinguisher on hand, prefereably dry powder or CO2.

Consider doig a cylinder drop test: set the engine to idle nice and high - about 2500 or so. With a tachometer visible, briefly remove each spark plug wire in turn. Note change in engine speed as a result...the one (or pair) with the least engine speed drop are weak...this narrows down your search. SAFETY NOTES: be careful pulling plug wires...you are likely to get a few shocks...if you can, pull the plug wire and offer the end an easy path to engine ground/earth. This reduces likelihood of you being path to ground, plus whenever you pull a plug wire off the current will find a path to ground/earth through the insulation on the HT system. Also note, if you have a Catalytic converter, this will get hot...leave a suitable interval between individual cylinder tests and minimise duration.

Good Luck.

Regards,
Munro.

[Kevin Smith]

Thanks for the caution. I've checked the 'balance' pipes that run from tappings on each port of the manifold to the plastic 'spider' that joins to the air cleaner and crankcase vent. I even disconnected them and blanked them off just in case it was a split hose.
I've tried the leak test on gaskets between the manifold and carb with WD40 (not sure if this is flammable enough to give a positive test), as best I could.
I think I mentioned previously that when I got my uncle to help by spraying Bradex Easy Start into the carbs (with the air cleaner assembly removed) the engine fired and attempted to run when fuelled on the Offside (RHS) carb, but only wanted to backfire (setting fire to my uncle's hand and the Bradex can on one occasion!) when squirted into the near side carb.
Additionally when I did manage to get the engine to run, I tried to balance the air flow between the venturis using a Gunson's Carbalancer. There didn't appear to be the same level of suction on the left carb as the right and I wasn't able to adjust the idle screw to rectify. Either there is an air leak after the left carb, or the valves weren't opening, preventing the cylinders drawing in mixture.
If I try to remove the left hand manifold I presume I'll have to drain out the coolant, which is a precursor to taking off the cylinder head.
I'll have to see what happens when I get chance to do it (Dark nights, busy weekends etc,etc!)

[Kevin Smith]

If anyone's interested I've got the LH inlet manifold off and there doesn't appear to be a problem with the gaskets.
I've got the radiator out and the LH cam belt cover off with view to removing the cylinder head that side. Removing the alternator and drive belt gave more room, and once I'd got the cam belt off I thought I was nearly there.
However it appears to be a bit more involved than first seems to get the head off in-situ. The cam tensioner doesn't go past the water pump pulley and I'm reluctant to disturb the water pump for the sake of it.
Does the cam belt tensioner pivot stud unscrew or should I be looking to remove the pulley from the water pump?
The back of the cam belt cover appears to have only two bolts that hold it onto the crankcase (and possibly more that fix it to the cylinder head, behind the cam wheel) and then the head is only connect to the engine with the head-bolts.
I've undone the top three off these quite easily but those on the lower side of the head look like they will pose a problem. Is the special tool I've seen mention of just a deep 17mm socket, or is it something more complicated?
I still need to lay under the beast to disconnect the exhaust manifold-hopefully the nuts won't be too much trouble?! Then we'll be in the land of dismantling the head and checking the valvelifters.

[Kevin Smith]

Asmentioned in a new topic I've finally got the head off. The screw that holds the bottom of the cam belt cover was so corroded it snapped my 1/4 drive 10mm socket trying to get it undone. Luckily the tin was so badly corroded that I was able to break the bottom part and get the head off.
Once I'd got the cam carrier off the head I found that two of the hydraulic followers appeared to be cracked around the circumference, about 1mm down from the crown. The other two appear to OK, and I assume that if the cracks prevent the oil pressure opening up the tappet properly then the two associated cylinders won't breath properly, leading to the symptoms I'd previously encountered.
I guess I'll have to find out from the local Alfa garage how much these things cost, and then decide whether it's cost effective to put the engine back together.

[Kevin Smith]

Finally cured the problems with my alfa 33!
It turns out that I'd managed to get the timing belt one tooth out for the left hand pair of cylinders. Once this was corrected the engine idled much better, but the guy who did the tune-up (Brian @ BJ Auto Services 01795 424 055) couldn't get the CO emissions right - it was running to lean and only getting between 0.1-0.2% CO. Eventually he located the problem which turned out to be the accelerator pump spray nozzles. Due to the car being left for a long period of time without being run these had apparently gummed up, but the orifices still appeared to be clear.
Once Brian had cleaned all four spray nozzles the CO came up to a more reasonable range 1.5-2.0% and he was able to get the performance back to its previous wheel spinning ability. Nice one, Brian.

[ak8635]

Hi Kev,
am having the same problems but mine is an ie model.

The idle is fluctuating at 750 and sometimes it drops to 500 and the the engine switches off.
This is combined with the very rough driving... acceleration is really abrupt and sometimes it just dies even though i am pressing the accelerator.
This makes driving the car in traffic unbelievable difficult..I was hoping it had to do with the gas but it is been going on for quite a while..
Have changed fuel filter, ht leads, spark plugs but to no avail..
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A112

[Maze123]

Hi there,

I have exactly the same problem with mine..
Kevin, the only thing you actually did, was that changing 2 of the hydraulic followers? Or was the timing belt in the wrong position all the time?
I have a 16v engine in my '88 33, and before it was swapped in it went through a major overhaul where one of the intake camshafts was changed. All the hydraulic followers looked fine at that time! The problem has been there all the time since it was swapped in, but after i tightened the screw on my AFM to reduce CO2 (I know that this isn't the right way to do it, but I'm short of time) it has become worse!

I suspect the following things to cause the problem:

1) Either a mis-placed timing belt or a pair of weak followers - the car has just been through a Delta HC test which showed, that the RPM-drop at cylinder 1 and 3 only is between 3,6%~5%, whereas at cylinder 2 and 4 it's between 24%~29% which is rather normal I guess.

2) The AFM. Hopefully just adjustment, but maybe it's broken...

3) Clogged injectors. My tank is rusty and it will be replaced as soon as the roads are a drier. As mentioned in this topic:
http://www.alfa-pages.co.uk/viewtopic.php?t=2021
rust from the tank can cause faulty injectors, but in this case, it should only be the injectors at cylinder 1 and 3 which have been clogged.

4) Last possibility is the distributor. I've checked the spark plugs etc., and the spark looks good in all 4, but I haven't checked the timing yet!

If anyone has other ideas to what may cause this problem, I will be glad to hear about it! I will post news about this topic here as soon as there are news about it..

Regards Mads
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Alfa 33 1.7 16v '88 QV
http://www.bilgalleri.dk/html/gal_visbil.asp?ID=2498

[Maze123]

Just found this:

http://www.alfa-pages.co.uk/ml41.htm

Check the part about the throttle position switch! Do you think that could cause the problem..? I mean, if its broken or faulty and reports closed throttles even though they are opened just a little bit (as they would be at 1000~2000 rpm), the ECU would reduce the fuel-supply, wouldn't it?!?
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Alfa 33 1.7 16v '88 QV
http://www.bilgalleri.dk/html/gal_visbil.asp?ID=2498