Returning to the head.. again..

Keep it on topic, it will make it easier to find what you need.
Shadoobie
Posts: 113
Joined: Mon Mar 03, 2014 10:07 pm
Your car is a: 1979 Pininfarina Spider 2000

Returning to the head.. again..

Postby Shadoobie » Tue Jun 06, 2017 9:22 pm

Hello everyone, just replaced my head gasket under your advisory and found that one of the head bolts was loose when taking the head off. The same bolt sheared off when I went to put the head back on, so I decided to buy all new head bolts. We never re-tourqued the head when we took it off the first time, so this doesn't really surprise me. I put everything back together and had no problems, even driving the car (very gently) 250 miles or so to a car show and back over the weekend. On Monday, I drove the car to work and found that it suddenly ran rough, just like the first time, except with the added bonus of smoke spewing out of the pcv hose. No valve clatter this time though, as well as no oil in coolant or vice versa. I got it home and ran a leak down test. I found that cyl. 1 is leaking from the exhaust, cyl. 2 from the intake, cyl. 3 from the exhaust, and cyl. 4 seemed fine. Then I ran a compression test, with the results reading thus from 1 to 4: 170, 165, 50, 150. I called up Matt Brannon and he suspected that the valves have bent or lost their seal somehow, which makes sense. However, all the timing marks line up perfectly for the cam, crank, and aux shaft. So what's going on?! And how?

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So Cal Mark
Posts: 13839
Joined: Wed Jan 25, 2006 3:45 pm
Your car is a: Fiat
Location: upland, ca.

Re: Returning to the head.. again..

Postby So Cal Mark » Tue Jun 06, 2017 11:25 pm

what percentage of leakage do you have on the cylinders? No cylinder seals perfectly but obviously #3 is a big problem
Mark Allison
allisonsautomotive.com Fiat and Alfa Romeo parts and service. Performance parts our specialty!
Headers, ignitions, wheels, cams, flywheels
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Shadoobie
Posts: 113
Joined: Mon Mar 03, 2014 10:07 pm
Your car is a: 1979 Pininfarina Spider 2000

Re: Returning to the head.. again..

Postby Shadoobie » Tue Jun 06, 2017 11:33 pm

So Cal Mark wrote:what percentage of leakage do you have on the cylinders? No cylinder seals perfectly but obviously #3 is a big problem


It ranges between 60 to 85 percent.

Shadoobie
Posts: 113
Joined: Mon Mar 03, 2014 10:07 pm
Your car is a: 1979 Pininfarina Spider 2000

Re: Returning to the head.. again..

Postby Shadoobie » Tue Jun 06, 2017 11:37 pm

I also noticed that cylinder 4 causes air to escape from cylinder 2 when tested. Is that a result of overlap of valves opening at the same time between cylinders? How does that even happen?


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