25 replies to this topic

[maystro]

Hi,  

 

My Mini engine sounds like it is running on 3 cylinders.  

I recently replaced the timing chain and gears which is on another thread here but that shouldn't be related I don't think because other than a tappety noise it has been running great with heaps of power.  

 

I checked and changed the plugs.  All have spark.   I have a new electronic dizzy and coil which was installed before things went a amiss.  

The head is fully recond about 6 months old which I did have a head gasket problem at first when I first put the new head on but I flattened out the block with a stone and put the best new head gasket available for a 998 and this seemed to have fixed that issue.   

 

There is no oil in the coolant or coolant in oil but I did notice a slight milky film on the rocker cover cap, no where else in the rocker cover.

Also their is a fair bit of smoke blowing out of the crankcase vent which on my motor is attached to one of the tappet side cover plates.  

 

Any ideas or thoughts of what I should do?

 

I'm thinking I just wasted 2 grand on a old 998 when I should have been looking for a second hand 1275?

 

Thanks
Brad

[whistler]

Check the valve clearances.

[Johnmar]

Not nice to hear after you've spend 2K..

 

It could be mechanical:

Check the valve clearances.

 And do a compression test so you can see what cilinder/valves you have to look into.

 

Or still electronincs related:

- The (changed) sparkplugs look OK (not that one is looking different in colour)?

- What is the condition of the HT leads ? (one could be kinda OK on idle, but could not be up to the challenge when you rev the engine perhaps.

- How is the Dizzy cap and its connections (intern and externally)?

Edited by Johnmar, 27 October 2020 - 10:03 AM.

[PACINO]

what kind of dizzy did you put on and what coil?.

[sonscar]

Carefully pull the plug leads whilst running,a duff cylinder will have no effect.If you find a cylinder off change the plugs for one of the good cylinders,does the duff cylinder move with the plug?You may have two cylinders off 1 and 2 or 3 and 4,head gasket!As said find dead cylinder check tappets.Excessive smoke from breather does not sound good.You could have bought a 2nd hand 1275,fitted it and found it too was borked,I have only bought two "Good" second hand engines and both were sick,Good luck,Steve..

[maystro]

Guy's

 

tappets have been done 3 times. 

number 2 and 3 plugs look a bit oiler than 1 and 4.  

 

I must admit I bought one of those cheap dizzy's on the internet and some sports gold coil.  I think it was a 59D4 Aplus with vac adavance.  I will definitely be buying one of those 123 dizzys for my next motor where you can select advance curves.  But  I don't want to waste anymore money on this engine if it is passed its used by date.  

I won't know if I'm getting a 1275 A or A+ so don't want to waste more money on this motor?

 

Thanks

 

Brad

[maystro]

Carefully pull the plug leads whilst running,a duff cylinder will have no effect.If you find a cylinder off change the plugs for one of the good cylinders,does the duff cylinder move with the plug?You may have two cylinders off 1 and 2 or 3 and 4,head gasket!As said find dead cylinder check tappets.Excessive smoke from breather does not sound good.You could have bought a 2nd hand 1275,fitted it and found it too was borked,I have only bought two "Good" second hand engines and both were sick,Good luck,Steve..

Yeah Sonscar I noticed when I pull the lead of number 1 it makes no difference to the sound of the engine unlike all the plugs.

 

Brad

[PACINO]

In my case when the engine sound changes and I suspect it is on 3 cylinders, I put these spark plug pipes with flashing light. I start the engine, and immediately see if there is something irregular in any of the cables.



It can be left on 3 cylinders simply because of a malfunctioning spark plug or the spark wire.

Regards

[sonikk4]

Have you done a compression test as mentioned earlier??

 

The light film of mayo will be more to do with the engine not being run up to temp and driven a decent distance.

[maystro]

Okay I finally bought a compresion tester and here are the figures.
1-65 psi
2-70 psi
3-120 psi
4-120 psi

What's the verdict. Maybe a blown head gasket between 1 and 2?

Also is 120 high enough for the other 2 cylinders?

Thanks Brad

[sonscar]

Head gasket almost certainly running on 2 cylinders eh?Steve..

[timmy850]

Did you do the compression test hot or cold? Was the throttle 100% open too? Did you have the remaining plugs all taken out?

Does sound like a blown head gasket between 1&2

Mine blew between 3&4 a few months back and had similar readings.

Edited by timmy850, 30 October 2020 - 10:16 AM.

[sonikk4]

New head gasket time. While its off i would relap the valves to make sure they are sealing correctly. I know you said the head was reconditioned 6 months prior but ones mans recondition does not mean a lot without some further info.

[maystro]

Timmy those figures were with 1 plug out at a time and no throttle, does that make a difference?

[maystro]

Sonikk4, the head was a 12g202 head which was already fully ported with big valves. The new shop put new valve seats, seals and it had been running great for probably 2 months. It cost me a $1000 bucks so was pretty thorough. This is the second head gasket I have replaced since installing.

I might need to flatten the block better. I did do this last time with a stone but was unable to remove one of the head studs.