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compression test results


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well today was a productive day again.

i spent all day with a friend doing a compression test on the car.

we went cylinder by cylinder one at a time testing compression with no spark from coil and just crank turn over, then crank turnover with full throttle but no spark, to engine running and throttle blipped on and off to about 2k revs or so.

here are the results, as you can see theres problems from number 3 and 4.

the noise that i have been hearing that i thought was from the exhuast is in fact coming from cyl 3, as when we started the car without the number 3 ht lead disconnected the noise totally disapeared!!! reconnect the ht lead and its there.

the concensus after speaking to quite a few people today is its a burnt valve and the spitting is the exhuast gasses coming back in( i hope i got that right wayne!!) from the inlet valve?

so the plan is , do a leak down test ( i will need all the info on procedure, max pressure to be used etc) with help hopefully is to actually get the cam towers off, take off the head and check the valves, also take a look at the pistons and then depending on costs either redo the valves etc or just buy a complete new head unit from gary kemp and and exchange with my old one.

so after spending all that lovely time on my exhaust system i finally discover,.. it has nothing to do with it!

but at least im almost there now, and when the head comes out the manifold and aux manifold come out too, which means i can refit them with new studs and nuts, remove the wastegate and sort that out, fix the broken lug on the wastegate fitting to the silencer pipe flange, and have the mating surfaces machined dead flat on all the flanges before refitting.

well im not coming to hethel so at least this will keep me busy.

more info as it happens and a pdf photo how to in progress!

once again i have to thank the following for taking the time out of thier busy days to talk to me on the phone, these guys are what makes this place a fantastic club and community.

thanks to glyn-splashout, wayneb who took the time to call me from canada, troy halliday for the advice and help he also has given meand robin _evil fish who was amazed by the sound of the car and how quiet it went with the ht lead off! just proves im not mad!

thank you all again for your advice and help, you have saved another esprit from the breakers yard as i was almost at that point.



Edited by bigsi
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well i have just spent the past half hour talking with gary kemp, looks like im going with a total replacement top end assembly all prepped ready by gary and giving him my old one in exchange.

im still doing the leak down test as soon as i can, and if need be will also get upgraded pistons fitted also.

another upgrade is the later turbo with wastegate adapter and a water cooled turbo, this should make life easier! and lose any future wastegate problems. if i go down this route im going to donate my nice working wastegate to the fishy wastegate appeal for non sticking wategates!!

so the plan is wait for gary, remove top ends, send off and get replacement with all sundries, replace and fit upgrades, all over the winter! lots of fun.

now really looking forward to working on the car, however i am still thinking of pulling the engine so i can get to the frame work and clean it all up and then fit all new bushings and pipework, so prehaps a total rear end drop out might be a better option.

more to follow shortly.

as always thanks to those who have taken the time to help.


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Just before you do anything expensive, are you sure your compression is that bad. To do a compression test the engine should be (ie run for at least 10 min) and then the test should be done without the engine running (ie cranking) with wide open throttle.

If I understand your results your lowest cylinder when warm with WOT is 112 and your highest is 131 whilst a bit of a spread it looks pretty normal to me.

Before pulling the engine apart I would check each throttle is opening fully and not restricting the flow of air into the engine which could cause a low reading in one or more cylinders.


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the tests were very thorough, only one was done with the engine running, the first two are without the king lead connected so the engine wouldnt start, also the engine was run to temp prior to the tests.

one of the valves in the number 3 cyl is definately shot and it has to be done so do the tappets.

thanks for the advice but i was most thorough or should i say my mechanic friend was!!

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No problem Simon, hope you find the problem and fix it asap :(

I reconned one or more of your tappets had insufficiant clearance (too tight) and was causing combustion gasses back up into the inlet tract. :(

But it is difficult fault finding from 3000 miles away on the phone :(

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i think im may take the guys on their offers of help when it comes to taking the top ends off, also as i have no idea how to check the gaps on the tappets etc , i think its a wise idea to have someone do that. there isnt a mechanic i can trust enough around here to ompetently for me.

so hopefully one of the guys will be able to pop over one weekend and give me some schooling 101 style!.

be awsome if its just as you say wayne!!

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Hi Simon,

Sorry to hear about your recent diagnosis. It seams that problems with No 4 cyl is quite common with the S3 turbos. My no 4 cyl also has lost compression.(72 psi with throttle wide open, no spark. All others at 150 psi) But I'm pretty certain mine is head gasket or liner.

A friend of mine(Ajay) has a theory, that it could be due to detonation problems with No 4. He's on his third engine build, of which he's done himself, and I m pretty sure he said it's always been no 4 that's failed, for one reason or another. You'd have to talk to him, however, as he could do a much better job of explaining it all then I could.


The need for speed can be found with a Lotus

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Don't THINK about pulling the engine - DO IT!! It really doesn't take that long, and everything is SOOOOO much easier with it sitting on the Bench. Or even the floor... You'll need a gantry and a chain hoist as normal engine cranes won't reach far enough over the back of the vehicle to lift the unit out. Once it's out, there's no problems with accessibility and you aren't dealing with a dirty environment any more - also, the only real way to clean the unit and the engine bay is with it out of the car. It always seems to be a major move to lug the lump out, but it truly is the easiest solution. As for your compression tests, no.4 seems to have your major problem as far as compression is concerned. Disconnecting plug leads certainly shows where the noise is coming from, but not what it IS. Mine was making a horrible rattly noise last year, traced it to no. 4 cylinder with the plug lead trick - turned out to be the manifold gasket, but by then I had the engine spread over the bench...

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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  • 4 weeks later...

daz mentioned ajay's theory concerning the repeated failure of no.4 cyl. I had heard of this before. The possibility is that on some (and I stress some) of our cars there is no coolant flow out of the heater takeoff on the back of the head unless the heater valve is open. This may cause a stagnant flow area, and thus localized overheating in the no. 4 cyl. area.

Since i am running an electric water pump @ very low speed until the engine warms, I utilize a secondary pump (similar to a chargecooler pump) to pull coolant directly from that takeoff on the head, then to the heater.


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