Technical Bubbles died on the road

[usafstud]

Hi,

I decided to take the 500 out of storage to drive it to school and back to storage to get the engine running to get a oil chnage done.

On the way to the storage unit (15 minute drive), I went up a small hill (500 ft long, 10 degree incline), I felt something like a small pop and the engine seemed to go from 2 to 1 cylinder. I was able to get it down the hill and to a safe distance to park the car by keeping the rev up to prevent it from dying.

The car died on the side of the road. Before the tow truck came, I tried to checked out a few quick checks.

The 500 didn't restart even after 20 minute breaks.

The condensor wire is still intact.
The plug wires were all connected.
Fuses were all fine.
Fuel in the filter and it did flow out of it when disconnected.
Point gap looked ok, will recheck when I go back to the storage unit.

I replaced the condensor, coil wires, distributor cap, and points about 50 miles ago. I rebuilt the engine about 200 miles ago, and the head ago 50 miles ago since I didn't break it in properly and blew the head gasket. After replace the head gasket, I did retorque the head gasket a few months later.

I do know I have to rebuild the carb since the mixture srew isn't doing anything on the carb and making the engine run rich since the plugs get pretty dark.

I don't know if it is over heating since it was about 65 degree fahnreheit and the car was only out for about 10-15 minutes.

What do you guys think and what order should I check things out? I have a rebuild gasket kit ready in hand. I don't have a spare fuel pump in hand.

 

[usafstud]

Found out that the rocker arm assembly blew up. The bolt and nut that holds it down vibrated loose, which allowed for the rocker arm on the far side of the engine to walk up the bolt.

This caused the rocker arm on the side closer to the hood to be at a angle and break apart.

I am thinking that i should replace the bolts that holds the rocker arms because the two don't line up together. Anyone know where i can get this and the rocker arm?

 

[Bambino]

Cripes - this is not good - sorry to hear about it .

Luckily these engines have zero valve overlap or you may have been up for a head rebuild.

Try Fiat 500 Ricambi in Holland (www.fiat500ricambi.com). Nice guys, quick service, good prices and a wide range of parts.

They appear to have the rocker assembly in stock - part number MO1099, price 78.60 euros. The studs should be easily available virtually anywhere.

Chris

 

[oopsadaisy]

Oh dear...... not nice, but at least fixable.

Keep us posted.

 

[usafstud]

Would it just be stud and rocker arm replacement? The valves/springs and rocker arm rods were just replaced.

 

[Bambino]

The valves should be OK.

What I would do is replace the rocker assembly and probably both studs then, after tappet adjustment and with the rocker cover off, start and run the motor while watching the valve actuation. If the valves seem to go up and down OK and the stems don't look bent, leave well enough alone and enjoy driving the car.

Chris

PS: Might be worth locking down the nuts that hold the rocker assembly.

 

[usafstud]

The valves should be OK.

What I would do is replace the rocker assembly and probably both studs then, after tappet adjustment and with the rocker cover off, start and run the motor while watching the valve actuation. If the valves seem to go up and down OK and the stems don't look bent, leave well enough alone and enjoy driving the car.

Chris

PS: Might be worth locking down the nuts that hold the rocker assembly.

with extra stregth lock tite

 

[Bambino]

Or just two nuts on each stud - the top one acting as a locknut.

 

[usafstud]

Or just two nuts on each stud - the top one acting as a locknut.

bambino, if i remember correctly, the nut was still tight on the stud/rocker arm. i think the rocker arm and stud backed out of the head. what can i do to prevent this?

i also noticed some play on the stud side to side. would the head still be in spec?

 

[Bambino]

bambino, if i remember correctly, the nut was still tight on the stud/rocker arm. i think the rocker arm and stud backed out of the head. what can i do to prevent this?

i also noticed some play on the stud side to side. would the head still be in spec?

Uh-oh.

You can get the studs reamed and larger ones fitted, but you may be up for a new head. Because the head and crankcase are alloy, they are quite soft and prone to this type of thing if nuts and bolts etc. are overtightened. Heads are available for these engines - so are larger valves

I'd get a local, trusted mechanic to look at it and give you some advice.

Chris

 

[usafstud]

Can i fit a 600cc or 650cc head to my 500L engine? Seems like i can find the 650/600 heads but not 500 heads.

 

[Bambino]

The various 2 cylinder air-cooled engines offered over the years had the following capacity/bore/stroke

479cc/80.0mm/56.0mm (original 500s)
498cc/67.4mm/70.0mm (500D, 500F & your car)
594cc/73.5mm/70.0mm (500R, I think)
652cc/77.0mm/70.0mm (126)

The classic Fiat 600 was a 4 cylinder water cooled engine.

Because the bores are different, it would seem that you'll need a 498 head. Someone else may know for sure.

Chris