1.4i ZX compression figures..

[GMZX]

Hi,

Would anyone have the compression figures for a 1.4i TU3 (KDX) on a '97 ZX.

Did a compression test today and each cylinder recorded 120psi/8.2bar.

Thanks

[MattBLancs]

Don't have a petrol ZX Haynes (do have a diesel book) but looking in the 306 Haynes (3073) which covers the TU3 KDX 1.4 fuel injection (up to mid 1996 reckons Haynes)

No specific figure is quoted, nor is compression ratio listed sadly.

In Haynes' section on compression testing it suggests "below 10 bars can be considered less than healthy"

Also "a difference of more than 2 bars between any 2 cylinders indicates a fault"

So that suggests your figures are a bit low.

Matt

[ozvtr]

120PSI is not bad, for a 25 year old engine. If all of them read the same, then that's actually good. Did you do a "wet test"? Add about a tea spoon of engine oil to the cylinders and see if the results change.

Whether the results are good or bad depends on if you have any symptoms and whether you intend to do anything about it! Not sure you would spend the money to rebuild the engine anyway? Could be rings, could be liners, could be both.
But do the wet test first.

[GMZX]

120PSI is not bad, for a 25 year old engine. If all of them read the same, then that's actually good. Did you do a "wet test"? Add about a tea spoon of engine oil to the cylinders and see if the results change.

Whether the results are good or bad depends on if you have any symptoms and whether you intend to do anything about it! Not sure you would spend the money to rebuild the engine anyway? Could be rings, could be liners, could be both.
But do the wet test first.

Thanks for the reply. I've only done the dry test. If I get the opportunity I'll do a wet test as well. I only did the test to check the head gasket as the car runs well apart from a strange clacking noise which I'm struggling to get to the bottom of. It doesn't use oil or coolant and there's no mayo present. However, it runs out of steam a bit after 70mph so I did the test to see how worn it might be. Being the 1.4 means it probably isn't the fastest anyway. It's a good car in most ways and I've spent a bit making it right and it's a real survivor so I'd probably source a new engine or get the current one rebuilt over the winter.

[MattBLancs]

What mileage has it done? (I'd have thought distance covered have more if a serious bearing on it versus just age)

The other possiblity for poor compression is valves not seating, the difference between wet test and dry tells you if piston rings or valve seating (as the spoonful of oil helps the rings only)

I'm not too sure on quite how straight forward it would be, but I'd be thinking about seeking out a 1.6 (TU5) if getting into engine replacement territory. Go for an upgrade if going to all that trouble.

If it is valve seating then could take head off, relap valves into their seats (new stem seals as they're something that ages ) and that could get you back on track. I'm not sure if this is hydraulic tappets (would expect so) but valve clearances also worth checking if not.

Would guess it has a five speed gearbox (think some 306's and certainly 106's were lumbered with a 4 speed from memory???) but if not then suppose not surprising an 8 valve is getting a bit breathless beyond 70mph if 4th is it's longest ratio.

Know what you mean about "a survivor" - good on you for giving it some love

Matt

[Ross_K]

Would guess it has a five speed gearbox (think some 306's and certainly 106's were lumbered with a 4 speed from memory???) but if not then suppose not surprising an 8 valve is getting a bit breathless beyond 70mph if 4th is it's longest ratio.

They're five speed. In my testing on a private road, the 1.4 tops out at 100-105mph if the wind's blowing the right way

[MattBLancs]

Not bad going at all that for a 1.4

[Ross_K]

The things we do when we're young and stupid eh?

[ozvtr]

However, it runs out of steam a bit after 70mph so I did the test to see how worn it might be. Being the 1.4 means it probably isn't the fastest anyway. It's a good car in most ways and I've spent a bit making it right and it's a real survivor so I'd probably source a new engine or get the current one rebuilt over the winter.

70 MPH! And your complaining?
I have the multipoint fuel injected TU3JP in a C3 and I would not consider it a rocket. It's good on the highway but "boggy" around town. Needs a lot of stick work to get the best out of it. Auto box version is "satisfactory" for an auto (if your not too fussy) but again good out on the open road. I have no idea how people cope with the 1.1 version!!!
I like the little engine because its very easy to work on. It doesn't take up the entire engine bay! Timing belt is not that hard to change and nor is the head gasket. Overall a very user friendly engine. Not a bad engine if you are going to start "fiddling" with engines.
I have the 1.6 TU5JP4 in a C2 and that performs much better BUT Citroen tends to under gear them for better city driving and better acceleration, meaning it tends to over rev on the highway. Out on the open road it tends to be a bit "harsh" and unrefined. It revs out well but seems to be strained to do so. It tends to do better on tight "point 'N' squirt" driving where you only peek into the high revs. The TU3 is almost the exact opposite. It seems to like to cruise.
If you want a bit more fun in a Citroen engine, the absolute minimum I would recommend is the TU5JP4 1.6 engine! Again not a complicated engine but it seems very reliable. However if you want to "cut your teeth" on a simple cheap engine, the TU3 is highly recommended.
If you want to maintain and "mod" your own engine, steer clear of engines manufactured after about 2010. They became far more complicated and far more fragile!!!