Sierra Sapphire Cosworth No Compression
#1
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Hiya all, my boyfriend has a sierra sapphire cosworth and it has no compression in Cylinders 1, 2, 3, but 4 has 60psi he has had a full head rebuild, brand new inlet valves, also a new headgasket & Also when the cams are removed the compression comes back on all 4 but was weak. As soon they go in its gone again etc please help he doesn't know what else to try!!
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#2
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Firstly assuming the test is actually being performed correctly and with functioning tester...
If it has NO compression, then the valves are not closing.
For starters whoever rebuilt the head needs a bit of a slap, or certainly their work given a re-check.
Presumably he is doing a compression test because of other symptoms/problems too ?
It could be as simple as a lifter issue, or a complete and utter cock up with poorly installed valves.
If it has NO compression, then the valves are not closing.
For starters whoever rebuilt the head needs a bit of a slap, or certainly their work given a re-check.
Presumably he is doing a compression test because of other symptoms/problems too ?
It could be as simple as a lifter issue, or a complete and utter cock up with poorly installed valves.
Last edited by stevieturbo; 06-05-2015 at 03:14 PM.
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Demi Jehu (07-05-2015)
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Demi Jehu (07-05-2015)
#4
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Could possibly be the cams/timing belt not installed correctly.
If that's the case slap whoever fitted it lol comes back to same thing, valves not closing correctly.
If that's the case slap whoever fitted it lol comes back to same thing, valves not closing correctly.
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Demi Jehu (07-05-2015)
#5
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Hiya guys thank you for your replies;
It was Impulse Developments that rebuilt it.
Also he has checked all the timing & cams and they're fine!![Sad](https://passionford.com/forum/images/smilies/icon_sad.gif)
He just has absolutely no idea what to try next!!
It was Impulse Developments that rebuilt it.
Also he has checked all the timing & cams and they're fine!
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He just has absolutely no idea what to try next!!
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#7
I've found that life I needed.. It's HERE!!
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Has it got hydraulic or mechanical lifters in it?
If its been change to mechanical then they could be gapped incorrect causing what you are saying
Failing that then it does sound like its not timed up correct
If its been change to mechanical then they could be gapped incorrect causing what you are saying
Failing that then it does sound like its not timed up correct
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#9
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And no he didn't take it back to them as they was very blunt and rude! He asked them to sort it and they refused to take it back claiming the work was done perfectly !! We're just so confused!!
Last edited by Demi Jehu; 07-05-2015 at 11:35 AM.
#10
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This engine needs dropping off with someone who knows what they are doing now im afraid. A high pressure leak down test will identify the problem area very quickly.
Testing it with no cams in doesnt really tell you much about the compression as the inlet valves dont open to allow any air in to be compressed, but at least all the low readings were the same which bodes well.
A possibility is the lifters are overpressurised for some reason so they are opening the valves when the cams are tightened down. Maybe wrong lifters installed?
Another worry is the fact it has had new inlet valves. I wonder if the valve sealing was tested when they were installed as ive seen bent / mishapen guides on a YB before after valve impact, and new valves wont fix that problem.
Finally, thinking out loud, there are YB cams out there with 2x woodruff keyways.
Is he CERTAIN the cam timing is correct? Were they set using markers (woodruff key problem wont be fixed) or timed with full lift (Woodruff key problem wont be an issue)
Testing it with no cams in doesnt really tell you much about the compression as the inlet valves dont open to allow any air in to be compressed, but at least all the low readings were the same which bodes well.
A possibility is the lifters are overpressurised for some reason so they are opening the valves when the cams are tightened down. Maybe wrong lifters installed?
Another worry is the fact it has had new inlet valves. I wonder if the valve sealing was tested when they were installed as ive seen bent / mishapen guides on a YB before after valve impact, and new valves wont fix that problem.
Finally, thinking out loud, there are YB cams out there with 2x woodruff keyways.
Is he CERTAIN the cam timing is correct? Were they set using markers (woodruff key problem wont be fixed) or timed with full lift (Woodruff key problem wont be an issue)
Last edited by Stu @ M Developments; 07-05-2015 at 12:25 PM.
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Demi Jehu (07-05-2015)
#11
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The only clear issue he can see is that the lifters are empty indicating that the oil is not getting up to them, however going to try and prime the oil pump and pressurise the engine, the valves were all replaced because impulse messed them up badly, the guy that done the second lot of work has built 50+ of these engines and runs his own company doing so, the valves won't hit the Pistons as I am lucky enough to have forged Pistons with valve cut outs machined into the crowns. Woodruft key wise they are singles and when stripped down pics were taken for reference etc and timing all marks are spot on!!
#12
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Seems a bit of a confusing story...
Is this a 4wd engine? Was it long studded as part of the build?
Oil pressure can easily be built up without the engine running using a drill and adaptor in place of the distributor. Indeed it should be done before installing a YB engine to check all galleries recieve correct oil pressure.
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Demi Jehu (07-05-2015)
#13
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Sorry my mistake! It was not BUILT by impulse the head was recondition to which they lied and didn't do half of the work they claimed to have done and still charged me £540 sent it to someone else who noticed 3 dead valve springs all hydraulic lifters were knackered he recut a brand new set of genuine inlet valves and pressure tested it to make sure everything was good without the cams in place it tested good pressure. The engine was rebuilt by himself with 2 other fully qualified mechanics helping everything was checked then double checked to make sure it was correct. It's a 205 2wd engine now have reverted back to standard head bolts and a reinz fibre gasket just to make sure it is sealing
#14
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Without being rude...if whoever rebuilt the engine is a "qualified" mechanic etc....then finding the problem really shouldnt be difficult when he has the engine/car in front of him.
But either way, the valves are not closing correctly that is blatantly obvious from symptoms described, and lifters not getting any oil wouldnt have any impact on that
Whether cams are not installed correctly, valve seats cut too deep, wrong length valves, wrong lifters etc etc
Again, all basic stuff that he can check although he may need to remove the head again.
But also stuff that should really have been checked before installing the head in the first place.
But either way, the valves are not closing correctly that is blatantly obvious from symptoms described, and lifters not getting any oil wouldnt have any impact on that
Whether cams are not installed correctly, valve seats cut too deep, wrong length valves, wrong lifters etc etc
Again, all basic stuff that he can check although he may need to remove the head again.
But also stuff that should really have been checked before installing the head in the first place.
#15
The annoying ginger guy
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Tbh after reading all this the best thing I would suggest really is to either take the car to a specialist to get rectified, or if your partner is mechanically minded I would get him to take the head back off and get that checked by a specialist, as if you get too many monkeys playing about you could end up with more problems if the head work is poor
#17
Too many posts.. I need a life!!
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Sorry my mistake! It was not BUILT by impulse the head was recondition to which they lied and didn't do half of the work they claimed to have done and still charged me £540 sent it to someone else who noticed 3 dead valve springs all hydraulic lifters were knackered he recut a brand new set of genuine inlet valves and pressure tested it to make sure everything was good without the cams in place it tested good pressure. The engine was rebuilt by himself with 2 other fully qualified mechanics helping everything was checked then double checked to make sure it was correct. It's a 205 2wd engine now have reverted back to standard head bolts and a reinz fibre gasket just to make sure it is sealing
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