5 replies to this topic

[MiniNZ1340]

Hey all first time on a mini forum looking to get some advice, as this is my first car and i don't know much more then the basics any help would be greatly appreciated :)

 

I have an allegro 1340 engined mini. Yesterday it looked like i had water running out of a weld down the exhaust header coming from No. 4 cylinder, some of this was steaming up and the rest dropping down under the car. There is no sign of using water and did a compression check starting;

No. 1 = 133

No. 2 = 180

No. 3 = 174

No. 4 = 136

There is no sign of water in the oil or rocker cover and when removed spark plugs they all looked very similar in colour and no sign of water that we could see.

 

Q: Are these compression's normal for a 1340? or if not what should they be?

 

Thanks Jason

 

[nicklouse]

They should be a lot more even than that.

Something is not right.

[MiniNZ1340]

What is a normal pressure reading for and engine like this?

 Cheers

[Dusky]

Compression test results are very hard to compare. You have too many variables to take into account ( what tester you use, what starter, what camshaft ( they alter dynamic compression) , how well the battery was charged, was the engine hot or cold? thotttle wide open?,...)

.

 

BUT your results indicate something wrong on the outer 2 cylinders. Every cylinder should be atleast be within 10psi of the other. 

Could be valve seats, could be pison rings.. Pistons rings can be comfirmed by putting a bit of ol in the bore and then testing again if I recall right?

[carbon]

What is a normal pressure reading for and engine like this?

 Cheers

175-190 would be typical compression pressure for a 1340 running CR of about 9:1 and a fairly standard road cam

 

All of the readings should be repeatable to better than 5psi, and all should ideally be within a range (min to max) of about 10psi

[Alex_B]

Reset your tappets and retest, that may be causing your low compression, if not then a leak down test would be a good idea and see where the compression is going