Leaky Valves, Low Compression. Many Problems?

[Vive les Fulvia]

Hi,

I have a 1969 Rallye 1.3 which has been running rough for some time. There is a constant backfire, it's smoking 60 a day, I am sure there's fuel dilution, which might explain low oil pressure, there's no noticeable change in engine note when #4 plug lead is disconnected and the engine occasionally dies once it gets hot or even at times when it comes straight off choke.

The timing has been checked with an indicator bulb and a strobe light and appears to be OK. The carb spaces are cracked in places so there is a air leak. With rocker cover removed and the engine turned over fuel is being pushed out of the cylinders but more prominently from #4.

I had uploaded a couple of videos and any advice, or confirmation of my worst fears, would be greatly appreciated.

https://we.tl/t-9dvYJi3Azm
https://we.tl/t-ZzYgzYMIcp

[piggdekk]

I cannot see the video, but based on your description it is fair to assume You need to rebuild the engine. Would be good to measure compression before You disassemble it (or have it disassembled), so that You know a bit better where the issues are. A leak down test is also a good idea, but bottom line sounds like You are in for a rebuild. How many km's has the engine got?
Backfire and engine stopping when choke is removed (although I would not use it at all) may well be due to the cracked inlet manifolds. Unless You burnt a valve or have other serious mechanical issues if the 4th cylinder isn't firing it may as well be a problem with the carburator. Maybe a jet is clogged? Does it fire if You put a brand new spark plug?

[Huib]

Very strange. On the video it looks like fuel is coming out of the bolts. I want bolts like that.

Plugs are out. No suction.

My bet would be a leak in the membrane of the fuel pump. I am curious what others will say.

Although..... Than there would perhaps also be oil in the carbs. And ultimately the content of tank would be in sump.

[piggdekk]

Very good point Huib,
the fuel pump is my bet too and it is a very easy part to change, together with an oil change...
Maybe gasoline is thinner than oil and still flows through the bolts while oil cannot make it?

[lancia7550]

Shouldn't there be a lot more oil pumping around on the chain, cams and rockers? Maybe that engine is damaged due to oil starvation.

[Vive les Fulvia]

Guys. Thanks for all the replies. In answer to some of your points:

Compression tested and the dry values are 90, 90, 80 & 80. This seems low...? I am going to redo the test with another tester and perform it in the dry and wet condition. This should give an indicator on how well the valves are sealing.

I checked the carb float and there was no fluid inside. The jets were removed and cleaned/cleared with compressed air. No debris or evidence of oil was in the float bowl.

Spark plugs are new. Tachometer has 79800km,

Could the fuel coming from the bolts be an indicator that they've lost torque or the head has been off and they reused the bolts?

I'll check the fuel pump membrane for any splits. But I am curious to know how a faulty membrane can lead to fuel coming out of the bolts? If fuel is able to to migrate up the bolt then surely it is pointing towards a head gasket or the cylinder head itself being defective

I was surprised that there was no oil. I would expect to see a bit more oil when the engine is turned.

[Huib]

The compression looks ok for a cold engine lubricated by petrol. Even if valves are leaking it would hardly be on all 4 cylinders. At this moment compression would not be my main concern.

The video is not very clear but I doubt that the petrol would come from under the head of the bolts. There are tiny holes in the body of the rockers to lubricate the cams. I think it is coming from there. If so there is petrol in the sump instead of oil. Or maybe mixed with oil. What does the dipstick tell you?

[bmarler]

it's difficult to diagnose an engine based on these short video clips, but i think there may be a combination of things causing the rough running. start with an oil change so you know you have something to lubricate the poor engine. if the fuel pump is suspect use a temporary fuel supply and gravity feed the carbs. use new spark plugs and make sure the cap, rotor, condenser, and coil are functioning as required.
when you gravity feed the carbs be sure to check the level of fuel in the bowls of the carbs. any deviation from spec should be corrected before proceeding. if you think there are leaks in the intake tract you can use carb spray and point it around the spacers and mount areas to see if there are any changes in rpm.
poorly functioning carbs will cause excessive smoke from the exhaust. this is often confused with oil smoke. you must have good carbs and a tight intake tract or you'll be fouling plugs or have other issues with performance.

[Vive les Fulvia]

@Huib

The oil does smell like there is some degree of fuel dilution taking place, dipstick is above the max level, so there has been a slight increase in volume.

@bmarler
Oil, filter, plugs, points and condenser are all new. Only the HT leads and rotor arm are unchanged. I did the spray check and there is an air leak and upon close inspection the spacers appear to be cracked.

[piggdekk]

Bmarler and Huib are both putting You on the right path. If fuel gets into the oil You either have an issue with the fuel pump or with carburators float levels. Both are relatively easy to check. In fact if You bottle feed the carburators You can check both the level in the floats. If the carburators hold the level than the issue is the fuel pump. In any case You must change the oil, running contaminated oil will cause a lot more damage in the engine!