Help please. Check valve keeps failing.

This is the third check valve I replace in 2 months. This one only lasted 2 days, 50 miles. It is a 1984 Mondial cab, US edition.

The one that fails is always the one on the front bank. The rear is good.

It failed after leaving the car in the sun all day and then getting on the freeway. I could hear the louder exhaust noise and then the smoke from the hose coming out.

I can take the check valve out and put a plug there. But I am more concerned that there is another problem here. I went under the car and it is only a tube going to the exhaust, nothing complicated. The valve is just a flap inside. There is black gunk build up inside that keeps the valve open. Where is this black stuff coming from? The valve is new, not cleaned and placed back.

 

The plugs were changed during the 15,000 mile service by a Ferrari shop 5K miles ago. I'll pull them out and replace them with the Iridium while at it. If I find out that they were not replaced by the Ferrari dealer, I will start wondering about the timing belts as well and do the complete service.

I did a search on the forum and I can't find the Iridium part number for the 1984 Mondial. I see a lot of info on the carb cars.

Thanks for responding.

 

When I removed the plugs, I noticed that the rear bank had one plug that was loose. I practically removed it by hand. On the front bank (cabin), there were 3 loose plugs. One (2F) was 1 and 1/4 turn loose. (My daughter drew the Ferrari next to the plugs).

Can the 3 loose spark plugs cause the front bank to run hot/rich and blow the check valve?

According the the PO and Ferrari of Beverly Hills, the spark plugs and timing belts were replaced during the $4K service that was done in 2004, about 5K miles ago. But nobody could find the receipts for that work. Should I get suspicious and just do a full service?

Do those spark plugs look like they are 5000 miles old? They are very dirty. Is it because they were loose and exhaust got to them? Look at the extender on one of the loose plugs and compare to the one that was tight. What is the brown residue?

I ordered NGK Iridium plugs, they be here on Tuesday. Tomorrow I'll rent or buy the compression tester.

How about the plug extenders? Is there anything special about them? Can I get them from Napa? Part numbers?

Question: While cranking the engine, how do I avoid the ignition from firing? What do I disconnect? The coils have the connectors on very tight.

I don't want to drive the car now until I resolve this.

Thanks for your support.
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Where are the ECUs located in the engine bay? I will unplug them tonight before I do the compresion tests.

I will also replace the timing belts and tensioners soon. After looking at the plugs, I am not sure if the belts were actually changed in 2004 as the PO and Ferrari mechanics stated.

Thanks,

 

Here are the results of the compression tests.

1F 150.5
2F 150
3F 150.5
4F 159
1R 150
2R 150.5
3R 149.5
4R 149.5

Why is cylinder 4F at 159 psi while the rest at 150? I did this cylinder 2 times: both times were at 159.

The engine was rebuilt at 20K miles. It has 51K miles on it now. Is it possible that they changed one cylinder only and hence the difference? Just speculating here. Can there be a 9 psi difference in 30K miles of wear?

I did the measurements at about 74 deg F, close to sea level. I tried with the throttle open and closed, not much difference in measurements. I used a brand new Sears compression tester.

All the loose plugs (see previous posting) at the front bank are the ones at 150 psi and the only one that was tight was at 159 psi.

The vehicle passed emissions in California.

What else can I test? I'm at a loss now.

The autoparts store gave me NGK DR8EI7 as the Iridium part. But I tried them and they don't fit, they are too small for the thread on the heads.

The plugs in there now are: NGK BPGES. Tomorrow I'll go hunting for these in Iridium. Does anybody have the part number? It will save me some hunting.

Thanks in advance.

 

Hi Steve,

I worry because I already went through 3 check valves and I can't find out why. The smoke is annoying. :-(

My car has the black extenders. My understanding from searching posts is that these are resistive extenders. Will it be ok to use a BPR6EIX, since it is resistive?

Also, without starting a debate here... should I go with BPR6EIX or BPR7EIX? I don't drive agressive, more like a grandpa, very light footed. My cars last a looooooong time.

 

I finally got the spark plugs from two different stores. I got the BPR7EIX (NGK 4055) as they were much easier to get at the local parts dept. than the BPR6EIX. I gapped them all at 0.025".

After reading several posts on torque, I tried the different tips on tightening the plugs. My goal was to figure out why the spark plugs were loose from the Southern California Ferrari shop.

There are several posts about not needing to torque down the plugs, just 1/4 turn or 1/2 turn. I never torqued them myself on previous cars. But in this case, it was puzzling as to why so many loose spark plugs. I needed to figure this out.

My understanding is that the torque should be about 15 lbs/ft. When using anti-seize, about 30% less.

I put the first plug and turned it 1/4 turn. Then I used my torque wrench (the one witht the needle). It was torqued to about 5-6 lbs!!!!!

Then I turned it 1/2 turn and measured it. It as about 6-8 lbs!!!!!

Then I used the torque wrench. Torqued it to 10 lbs, 1/2 turn out and then torqued it back to 10 lbs. The torque stayed flat at 10 lbs for about 3/4 turns, so I did all the plugs at 10-11 lbs.

The plugs were able to reach the 10-11 lbs anywhere between 1/3 turn to 1 full turn. So the 1/2 turn non-torque rule of thumb tip works great for some plugs, but for the other plugs that needed 1 full turn, they would be loose. Which is what I suspect happened to me. The mechanic must have turned them at 1/4 or 1/2 turn. I agree with this if a torque wrench is not available, as it is better to tighten back a loose spark plug instead of ending up with a stripped head.

Before starting the engine, I removed and replaced the bad air check valve and attached a 6 inch hose to it not connected to anything. This way, I will be able to tell right away if (hopefully not "when") the check valve blows up "again".

Then I started the engine. It started right away! DANG!!! IT PURRSSSSS NOW!!!! And with the check valves now open, it has a nice loud noise. I like it!!!

Then I went for a drive around the block. WHAT A RIDE!!!! Is this really my car!???

I now understand why people praise the Iridium plugs. I'll use them on my Land Cruisers next.

As to the check valve, tomorrow I'll go to work and test it on the freeway. It is an 80 mile ride and the valve used to blow up half way to work or on the way back. Fingers crossed that this is solved.