Is my engine beyond saving ?

[MRGT]

Decided to have compression and leakdown tests down on my engine (2.5 16V)in order to see if it gives an idea as to the relatively low power figures and got the following results back

Compression (psi)
Cyl1:115, Cyl2:120, Cyl3: 115, Cyl4: 110

Leakage
Cyl1: 11%, Cyl2: 40% [&o], Cyl3: 14%, Cyl4: 40% [&o]

Smoke test carried out at same time and apart from very small seepage from exhaust manifold but nothing else, so some good news at least.

So, bearing in mind I am a mechanical numpty

1: Should I just enjoy the car as it is and stop worrying about being overtaken by 1.6D escorts ?

2: Is it worth while considering a rebuild ? or would replacing the whole engine be a better bet, and if so with what ? (no I cant afford one of those lovely Chevvy V8's ! )

3: Buy a turbo instead

Thoughts/comments appreciated as always

Howard

 

[Peter Empson]

You said in a previous post it was producing nearly 160bhp, which given the above isn't at all bad to be honest. Did they suggest where it might be losing it based on any noise they could hear? - I'd wager the top end rather than rings given the reputation of these engines wearing there.

If it was me, and oil consumption wasn't bad then I think I'd be tempted to keep enjoying it, I have less power than you (not that different dyno's are terribly accurate) and don't ever find it slow as such (which does makes me wonder if I'm missing something - you are using all the revs I assume?). I've not looked at pricing accurately, but I'd have thought a top end rebuild should come in at less than a thousand pounds from a good indie (unless you need valves), so if you're keeping the car then it's money well spent.

 

[MRGT]

ORIGINAL: Peter Empson

which does makes me wonder if I'm missing something - you are using all the revs I assume?

Damn ! thats where I'm going wrong, I keep thinking Ive still got my diesel ! []

I do enjoy driving her but she does feel a little sluggish (even when allowing for the fact I've just come from a 170hp turbo diesel with its oceans of torque) hence the reason for getting her on a dyno initially. I am one of those people who, when they know something isnt quite right, will not be able to sleep at night wondering how to fix it [] hence the 'thinking aloud'

As she uses very little oil and doesn't smoke (much) I am inclined towards the idea that it is more likely top than bottom, I may ask around and see how much a top end rebuild will be and take it from there. Whichever way it goes I wont be getting rid anytime soon as she is just in too good condition to let go.

 

[Diver944]

Barry Hart from Hartech has spoken quite frequently on other forums that the 2.5 16v engine is very prone to wear in the valve guides due to the length of the valve itself. This could well account for many of the S models being quite a bit down on power when measured. If your belts are due a change anytime soon then it could be wise to combine both operations and save a little bit on labour at least.

 

[bw64870]

Better results than my leak down test . Thick oil and head in the sand and just enjoy cruising, thats my current solution. I am pretty sure mine is piston rings as there is heavy smoke under maximum load .

 

[zcacogp]

Out of interest, what's a leakage test and why do you have the (joint) highest leakage figure on the cylinder which shows the highest compression (Cyl 2) ?


Oli.

 

[924nutter]

Smoke under heavy load usually indicates "piston area" whereas a burst of smoke, which clears after a period of idle, usually indicates a worsening valve guide problem. Worn guides on their own wont cause a loss of power unless it gets so bad that the flame is being suppressed by large volumes of oil in the mixture, and without a second test after the addition of a little oil into the cylinder to see if the cylidner pressure rises we can't be completely certain but at the 944S's compression ratio I think the values are low across the board. I would think 147 psi as a minimum plus or minus five psi for an engine with sound piston rings.
A 944S is going to feel completely flat against 170 bhp t/d as it is not noted for its torque below 3800 compared to the 8v 944, but I found with mine that it was rather like having a lagless turbo over 3800... stamp on it and wind it round to 6800, keep it over 4000. Damn near as quick as a contempory bmw m3 and 928s couldn't catch me at Castle Coombe.

My citroen AX GT is quicker than a 1.6 turbo deisel

 

[MRGT]

Thanks for the replies folks, I suspect I am worrying over nothing but thats just me, anyway it gives me something to think about. Managed to dig out RR readout from a few months ago which shows the shortfall in torque and BHP.

@Oli, a quick guide as to what a leakdown test is can be found here http://autos.yahoo.com/maintain/repairqa/engine/ques057_1.html

@924nutter, I think the (my) problem here is that even above 4000 there still doesn't seem to be much in the way of go, maybe I need some driving lessons in order to get the best out of her [] ,anyone in Devon with a 944S I can borrow for comparison []

Thanks again

Howard

 

[zcacogp]

Howard,

Thanks for the link. Very helpful.

Sorry I'm not in Devon, and don't own an S - otherwise I would happily offer!


Oli.

 

[924nutter]

ORIGINAL: MRGT


Thanks for the replies folks, I suspect I am worrying over nothing but thats just me, anyway it gives me something to think about. Managed to dig out RR readout from a few months ago which shows the shortfall in torque and BHP.

@Oli, a quick guide as to what a leakdown test is can be found here http://autos.yahoo.com/maintain/repairqa/engine/ques057_1.html

@924nutter, I think the (my) problem here is that even above 4000 there still doesn't seem to be much in the way of go, maybe I need some driving lessons in order to get the best out of her [] ,anyone in Devon with a 944S I can borrow for comparison []

Thanks again

Howard

Again, looking at the torque curve, it is way down. If I read the grid properly you are showing 143lb/ft at 4450 rpm, whereas factory fresh it should be 170lb/ft at 4300, so no wonder you are embarrassed by 1.6 TDIs. At 10.9:1, which I have just looked up, you should see nearly 11 times atmospheric so think 165psi not 120.

 

[MRGT]

ORIGINAL: 924nutter
Again, looking at the torque curve, it is way down. If I read the grid properly you are showing 143lb/ft at 4450 rpm, whereas factory fresh it should be 170lb/ft at 4300, so no wonder you are embarrassed by 1.6 TDIs. At 10.9:1, which I have just looked up, you should see nearly 11 times atmospheric so think 165psi not 120.

Well, the reference to 1.6D Escorts was a little tongue in cheek, but yes you are correct with your reading of the graph. Now I dont expect anywhere near 'factory fresh' values, but if I can find a way to get it to within reasonable figures I will be happy.
Dont get me wrong though, I love her as she is, but like most of us I suspect we all want to feel something a little younger []