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Discussion Starter #1
Hi,

my 24v 1995 164 has developed a reluctant idle, which gets worse as the car gets warmer. Touch the throttle and all is well. Without manual throttle intervention it hasn't actually stalled on idle but sounds like it wants to.

I have just, as mentioned in other threads, replaced the injectors, cam gaskets and plugs. One of the intake runner boots is split but have sealed this with a non-setting gasket sealant which is holding. I confess to not replacing the intake runner to head gaskets but to re-using the originals, with a touch of sealant.
Haven't changed the front bank cam gasket/plug oil well seals yet - changed the plugs two weeks ago and one spark plug seal was showing the first signs of leakage; which may have got worse since... or not.

Apart from that the only other change I made was to junk the K&N for an new original air filter.

Any suggestions, please?

Thanks,

Richard
 

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Refresh my memory did you verify cam timing yet with timing dies or visually check cam timing marks with engine at Top Dead Center and valve covers off?

Since you said you haven't had front covoer off I guess not there but did you verify rear cam timing when you had cover off?
 

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Discussion Starter #3
Refresh my memory did you verify cam timing yet with timing dies or visually check cam timing marks with engine at Top Dead Center and valve covers off?

Since you said you haven't had front covoer off I guess not there but did you verify rear cam timing when you had cover off?
Hi Steve,

and no I didn't but don't think it is a timing issue.

When on idle there comes a definite point as it warms up when the idle, never smooth, suddenly takes a turn for the worse. To me it sounds like some dynamic failure rather than a fixed cam belt error.

Thanks,

Richard
 

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Hi Steve,

and no I didn't but don't think it is a timing issue.

When on idle there comes a definite point as it warms up when the idle, never smooth, suddenly takes a turn for the worse. To me it sounds like some dynamic failure rather than a fixed cam belt error.

Thanks,

Richard
Maybe you need to check hot and cold resistance on coolant temp sensor maybe resistance is staying to high when engine warms up and causing to rich a mixture? You know where it is right - In mid thermostat housing.
 

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Discussion Starter #5
Maybe you need to check hot and cold resistance on coolant temp sensor maybe resistance is staying to high when engine warms up and causing to rich a mixture? You know where it is right - In mid thermostat housing.
Actually, might be a corroded/dirty connector there as previously spilt coolant on it.

Thanks, will check it out,

Richard
 

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It could also be the coil-packs jumping spark to the heads... Do you hear a ticking sound up-front? It is a known-issue - you can take the coil-pack cover off up front and see the light-show!

There is a fix - something about using a sheet of dielectric/dialectic material to cut sections and insulate the coils from the valve covers (as well as the inside of the spark-plug holes) to prevent arcing...

It creates a stumbling feel to the idle that seems to go away with higher revs (but I am sure that it is still there - just less noticeable due to the high coil-duty cycle at that point...)
 

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Discussion Starter #7
It could also be the coil-packs jumping spark to the heads... Do you hear a ticking sound up-front? It is a known-issue - you can take the coil-pack cover off up front and see the light-show!

There is a fix - something about using a sheet of dielectric/dialectic material to cut sections and insulate the coils from the valve covers (as well as the inside of the spark-plug holes) to prevent arcing...

It creates a stumbling feel to the idle that seems to go away with higher revs (but I am sure that it is still there - just less noticeable due to the high coil-duty cycle at that point...)
Thanks for that. Not noticed a 'ticking' but doing the front bank cam cover shortly and will check it out.
 

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Discussion Starter #8
Just changed the front bank cam cover gasket too and took the plugs out (new ones) to double check they were clean. Bit of oil had seeped past one so probably hadn't tightened them up enough when putting them in.

All back together it is running smoother now but idle still low and bit lumpy. Some belt squeal - seems one bearing on the auxillary belt is finally giving up the ghost; at least now I should be able to feel which one it is as a year ago they all felt fine, despite some intermittent noise. Question: could a rough bearing be causing drag on the engine and making the idle low/slow?

Thanks.
 

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Check wiring to injectors. I have similar problems at idle and sometimes driving comes and goes. As the car heats up it gets worse guessing the wire gets mushy and loses connection. I have to open up the loom and repair the wire. Easy check wiggle the wire and bend them to see if the idle changes. Mine turned out to be the rear middle injector wire.
 

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Power module

I had a miss on my engine most noticable at idle. I replaced one of the two power modules located on the base of the air cleaner frame. The rough idle was cured. It is G131 on the wiring diagram.
 

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Discussion Starter #11
Check wiring to injectors. I have similar problems at idle and sometimes driving comes and goes. As the car heats up it gets worse guessing the wire gets mushy and loses connection. I have to open up the loom and repair the wire. Easy check wiggle the wire and bend them to see if the idle changes. Mine turned out to be the rear middle injector wire.
Thanks, will try that.
 

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Discussion Starter #12
I had a miss on my engine most noticable at idle. I replaced one of the two power modules located on the base of the air cleaner frame. The rough idle was cured. It is G131 on the wiring diagram.

Hi, already tried swapping them over, front and back, but my initial problem remained on the rear bank so seems unlikely to be this, although will take another look.

Thanks.
 

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Discussion Starter #13
update

Hi,

took the Alfa (24v) for a spin and tried it at various revs and throttle settings.

Have concluded thus:

1) Power is good, judging by the way squeezing the throttle in first at 3000 rpm causes the 205 tyres to complain.
2) What I thought was a metallic vibration at 5000 rpm actually appears to be some kind of gas leakage - at 5000 rpm it is well on cam, hence more gas flow (gas in this case being the European 'gas' not American for fuel/petrol); could be intake or exhaust. Mostly suspect exhaust and wondering if possibly broke something when removing the rear cam cover - which included removing the exhaust 'reflow' pipe.
3) Exhaust gas leakage is also suspect as it is very loud from the outside when booted - judging by the heads turning on an overhead bridge.
4) Admit haven't checked the cam timing but all the indications are, to me, that it is fine.
5) Drivetrain shunt at sub 1500 rpm - in all gears.
6) Idle gets worse as car warms up - still need to check the thermostat temp sensor for corrossion but apart from that am a bit stumped.

Any ideas?

Thanks.
 

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My Experience

My 95 LS was also exhibiting a rough idle. After much work, it finally turned out that with 11,000 miles since a timing belt change, 3 of my 4 cams were out of time when measured by cam locks (two slightly and one by a bit less than one tooth).

According to my mechanic, marks on the cams lead him to believe that when the belt was replaced (by the former Alfa dealer in Albany, NY, which shall remain nameless but is located in Burnt Hills, NY) that the cam timing may not have been checked with the locks and instead the cams may have simply been clamped into place where they were. Either this or belt stretch over 11k miles (or both) put the timing out.

Now that its fixed, the car is a revelation. My mechanic said it changed his view of 164s, which he had never particularly liked before. He has, however, humored my obsession with the Galvanized Alfa with excellent workmanship.

Keep looking for the problem. The reward when it finally runs right is well worth it.

Rex in Albany
 

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With all else in order and rough running still an issue my money is on valve timing. I too was made a believer in timing dies after I used them to straighten out Myron's 95LS and he still brags on me for fixing his car.
 

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Discussion Starter #16
My 95 LS was also exhibiting a rough idle. After much work, it finally turned out that with 11,000 miles since a timing belt change, 3 of my 4 cams were out of time when measured by cam locks (two slightly and one by a bit less than one tooth).

According to my mechanic, marks on the cams lead him to believe that when the belt was replaced (by the former Alfa dealer in Albany, NY, which shall remain nameless but is located in Burnt Hills, NY) that the cam timing may not have been checked with the locks and instead the cams may have simply been clamped into place where they were. Either this or belt stretch over 11k miles (or both) put the timing out.

Now that its fixed, the car is a revelation. My mechanic said it changed his view of 164s, which he had never particularly liked before. He has, however, humored my obsession with the Galvanized Alfa with excellent workmanship.

Keep looking for the problem. The reward when it finally runs right is well worth it.

Rex in Albany

Many thanks for that and glad yours got sorted.
I am still reluctant to believe it is the cam timing with mine due to the way it drives generally and the fact that the idle gets worse as it warms up. It also seems to be drinking petrol so may well be running too rich - aiming to check the temp sensor on the thermostat housing.

If it does, in the final account, turn out to be cam timing, I will buy a rice hat and eat it :)

Cheers,

Richard
 

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Discussion Starter #17
Maybe you need to check hot and cold resistance on coolant temp sensor maybe resistance is staying to high when engine warms up and causing to rich a mixture? You know where it is right - In mid thermostat housing.
Thanks again Steve,

that is next on my list.

Will post the results.

All the best,

Richard
 

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Yea I replaced Valve cover Gaskets on my "92" L and My intake runner bolts are stripped!!! I could barely get them off I couldnt get # 2 off going from right to left and I wanted to replace the little gaskets because it really needs them!!! Well I finshed installing the front and rear valve gaskets along with sparkplug well gaskets. Now im worried because I had to reuse those old allen screws and the old gaskets as well. and now intake #5 has a stripped thread man I was bummed out!! Its about 97 degrees and the only shade I have is my hood. I installed #6. I turned car on and a good whistle from number 5 where the screw is stripped luckly its the outside screw I got the 1223 but the cause was obvious. SOOO what I did was I unscrewed the long philps screw from upper driverside (where handle is located on passenger side) and a nut that fits it, I pushed that screw through the intake runners hole and held the nut with a flathead screwdriver and some sealant to keep the nut from falling in the V of the engine well I tightend it up and it sealed. I turned the car on and it idled nicely. But I have a feeling that there are little air leaks because those gaskets are so old. I want to replace all those little gaskets and those old screws as well I just want to know what size are these I was thinking they were 1/4 20 but didnt want to take any chances. Does anybody know what the sizes are and What can do to pull the stripped allen head on #2?? I was thinking of tapping #5 but its kind of hard to fit a tap in there.
 

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Effect of Temp on Idle

One of the confusing symptoms of my 95 LS was that the idle got really bad when the engine temp rose to the upper end of the operating range, such as happens in stop and go traffic.

The other thing I really remember was that you had to be very careful as you fed it gas and slipped the clutch to start. Everything would seem to be OK and then the car would literally skip a beat, which could cause you to look like you dumped the clutch if you weren't very careful. This alone made the car very annoying to drive.

But now that its fixed I also notice that the engine spins and sings much more happily throughout the rev range.

By the way, my mechanic did not think the cams were out when he did a visual inspection. The cam locks revealed the truth. But even then, he was pessimistic that the small amount by which the timing was out could be the cause of the problem. It was.

He observed that the 4 cam units have huge timing belt, whereas other 4 cam motors he works on (Ferrari) use two belts. The problem with one large belt is that it can stretch over time, causing timing to drift. My belt only had 11k miles on it and was set (perhaps shoddily) by the former Alfa dealer in my area.

Of course, your actual mileage may vary.

Rex
 

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The gaskets should be used only once, as usually they are designed to crush a little when used, and this prevents reuse without risking leakage.

It's easy to check the size of the bolts by just going to a big outlet of screw and bolts and comparing side by side. Many outlets now carry metric allen bolts of this ilk. You can also use hex head bolts if you have 1/4th inch drive sockets.
 
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