Alfa Romeo Forums banner

1 - 20 of 39 Posts

·
Registered
Joined
·
96 Posts
Discussion Starter #1
I just picked up my new-to-me '91 S, and it doesn't run well. The only problem the PO mentioned was that the "car missed occassionally". The engine isn't "missing", but it idles and runs rough and has a lack of power. I can see from the repair receipts that the rotor, cap, wires, and plugs were replaced 500 miles ago. Timing belt was changed 3000 miles ago. I checked the engine codes, and there are no stored codes. I couldn't find any vacuum leaks. I checked plugs 4, 5, and 6. Five looks normal, but 4 and 6 look a little gray to me.

My mechanical experience is somewhat limited. I've owned several 2-liter Alfas, and I've replaced several head gaskets and clutches, and various other procedures. The 164 engine is quite a bit different.

Any suggestions as to what to look for?

Thanks.
Greg
 

·
Registered
Joined
·
4,090 Posts
Ok, I'll say it first. Check cam timing. Belt could have slipped which is the recipe for bent valves. Some get away with a tooth or two. If belt has slipped, reset, and test compression if it still doesn't run right.
Jes
 

·
Registered
Joined
·
96 Posts
Discussion Starter #3
Thanks for the reply.

I'm hoping that isn't the case. I thought about checking the timing, but that seems a lot more complicated than on a spider.

I'll try a rule out the easy stuff first.
 

·
Premium Member
Joined
·
9,741 Posts
Thanks for the reply.

I'm hoping that isn't the case. I thought about checking the timing, but that seems a lot more complicated than on a spider.

I'll try a rule out the easy stuff first.
Sounds like timing.
Print this template out and check timing.

Below

Here is a complete write up on the whole change just for fun. It is pretty easy after the first time
http://www.alfabb.com/bb/forums/showthread.php?t=46892&highlight=timing+template

Don't drive it anymore until you are 100% sure it is not timing.
Ciao!
Jason
 

·
Registered
Joined
·
8,770 Posts
I'll say it 3rd...better check the valve timing. You could start with checking the compression, that's easy and it may give you an indication of bent valves.
Is this a 12V, or 24V?
 

·
Registered
Joined
·
96 Posts
Discussion Starter #6
Jason,

Thanks for the reply.

The first link you post didn't work. I have the CarDisc manual so I guess the proceedure is in there.

Is there anything unclear in the manual?

Thanks,
Greg
 

·
Premium Member
Joined
·
9,741 Posts
Print this out at 100% and align the crank and TDC, check cam marks.
Here:
 

Attachments

·
Registered
Joined
·
8,770 Posts
Here's the link for the timing template:

http://www.alfabb.com/bb/forums/atta...6&d=1179330802

It's not in CarDisc or the manual, but many thanks to a BBer. It works really well. Make sure you print it full size on 8.5X14 paper. I laminated mine. Cut out the 2 circles for the cam gears. Set the crank on the timing mark, with #1 at the top of the compression stroke. Pop the 2 plastic caps covering the cam gears. The circles you cut out fit on the cam gears. The marks on the cam gears should line up with the 69 deg and 72.5 marks on the template.

Good luck
 

·
Premium Member
Joined
·
26,810 Posts
Jason,

Thanks for the reply.

The first link you post didn't work. I have the CarDisc manual so I guess the proceedure is in there.

Is there anything unclear in the manual?

Thanks,
Greg
Here is direct link to my post that Jason linked to. His link worked for me but if it didn't for you try this one and click on links within for template and TDC mark, etc. http://www.alfabb.com/bb/forums/showthread.php?t=46892

You really need to verify cam timing and compression first off in either order but those are the first steps.

YOU CAN CHECK CAM TIMING WITH TEMPLATE with engine and car still assembled. You just need to remove center black caps on timing belt covers and right wheel and inner fender liner to access crank shaft front pulley (for safety sake do not use flywheel mark on USA models).
 

·
Registered
Joined
·
96 Posts
Discussion Starter #12 (Edited)
I really appreciate all the help. I won’t have purchased another Alfa without knowing that there are so many willing to help on this forum.

I was having some internet problems, which have been solved. I now have all the links and I’ve printed Rick’s template. I should have some time on Monday to work on the car, I’ll report back with my findings.

Greg
 

·
Registered
Joined
·
8,770 Posts
None of us like having a non running Alfa...Most of us have been through it. We feel your pain and concern... Good luck with it.
 

·
Registered
Joined
·
96 Posts
Discussion Starter #14
I got a chance to work on the car tonight. The cam timing is correct, and here are the results of the compression test:

1 170
2 170
3 160
4 160
5 175
6 160

Now that I knew the timing was okay, I took the car out for another drive. It runs roughest at about 2000-2500 rpm, and then smooths out a bit. The car is still fairly quick; this is the first 164 I've owned, so I'm not familiar with the performance or the sounds. It sounds odd at those rpms, like it's running rough, not smooth.

Any more ideas? Thanks a lot for all your input.

Greg
 

·
Registered
Joined
·
8,770 Posts
OK, the compression looks good and the timing is Exactly on the marks, right?
It's an old car new to you.
Some problem areas have been:
1. If the upper wishbone motor mount rubbers are worn out and the engine is moving to much, sometimes the tight wiring to the temperature sensor can loose contact. Check your upper motor mounts for deterioration. Check the Bosch temperature sensor connector, located under the thermostat housing.

2. Is the micro switch on the throttle working and set properly.

3. Is the idle actuator working?
 

·
Registered
Joined
·
4,090 Posts
Have you checked cap & rotor? I see you said there are receipts, but a double check is quick.
Jes
 

·
Registered
Joined
·
96 Posts
Discussion Starter #17
OK, the compression looks good and the timing is Exactly on the marks, right?
It's an old car new to you.
Some problem areas have been:
1. If the upper wishbone motor mount rubbers are worn out and the engine is moving to much, sometimes the tight wiring to the temperature sensor can loose contact. Check your upper motor mounts for deterioration. Check the Bosch temperature sensor connector, located under the thermostat housing.

2. Is the micro switch on the throttle working and set properly.

3. Is the idle actuator working?
The timing lined up exactly, if you can call a paper template exact. I'll need to print one on harder stock.

1. I wondered about the motor mounts. If the engine moves too much, could I preceive vibration as rough running? I'll check the motor mounts tomorrow.

2. I don't know anything about the micro switch; I'll have a look at the shop manual.

3. How do I know if the idle actuator is working correctly?


Have you checked cap & rotor? I see you said there are receipts, but a double check is quick.
They replaced them in April, 500 miles ago. I'll check them tomorrow.

Thanks for the replies.

Greg
 

·
Registered
Joined
·
8,770 Posts
I doubt you would mistake bad motor mount for rough running, but checking the Bosch temperature connector under the thermostat housing would be a good thing to do. The spade connector is for the high temperature light. The Bosch connector is the one your looking for. Its for sensor. When you pull the connector, look for strained, tight wiring and also look inside the connector for bad connections and loose wiring.

The micro switch is at the end of the big black hose at the engine, not the air filter end. It faces the front of the car. It was 2 wires and a connector. It has an 8mm bolt securing it. Loosen of the bolt and it will rotate. Turn it all the way counter clockwise, the very slowly and carefully turn it clockwise until you hear it click and lock it in place.

To check the idle actuator, remove it from the center rear of the air box. Make sure the rubber seal is in place, fits tight in the hole in the air box and is in good condition. You can clean it out with carb cleaner.
 

·
Registered
Joined
·
3,506 Posts
Pull one of the small tubes on the intake manifold, like the one on the fuel pressure regulator. Blow into it. You should be able to put a few cubic inches of air in there, enough so you feel a sensible over-pressure. It should stay there a few seconds (block the tube with your finger or even your tongue), and when you release the tube you should feel some of the air come back out. If the overpressure disappears immediately, then I'd say you have an air leak somewhere. You can try tying an air-filled balloon on the tube (whichever one you use) and then you will have a bit of time to hunt for wherever the air is leaking out. Check the seal on the oil filler cover and the (hard to get at) oil separator return.

Check the fittings at the spherical vacuum reservoir for the cruise control (left front wheel well fore from the wheel). You'll probably have to take the gravel shield off. I've seen these tubing pieces break or come off and provide an air leak. The ends are far removed from the intake manifold and hard to hear leaking while shielded way down in the fender area.

And I thought I'd read that 200 psi was a more reasonable compression reading. I haven't re-measured my wife's car's engine compression since break-in, but brand new before running in I was getting about 160-170, as I recall.

Michael
 

·
Premium Member
Joined
·
26,810 Posts
If you did compression test with throttle body butterfly closed those numbers about right but if you held throttle open you may get higher readings.

Have you tried to verify intake air tube between throttle body and air flow meter is crack free? Quick test is with engine idling move air flow meter up and down and see if idle changes if so look for crack in corragated tube.
 
1 - 20 of 39 Posts
Top