dannytattersall

Hi to all, I am trying to diagnose a problem with my Mk1 Escort, fitted with a RS Cosworth turbo engine, and would appreciate any suggestions. It has not been used on the road since returning from a rolling road session in October last year, where there was no smoke whatsoever from the exhaust despite undergoing a full power run at over 7000 rpm. I did not start the engine for a couple of months after the rolling road session but since then it now emits a significant amount of blue smoke from the exhaust once fully up to temperature, in particular when the engine revs are increased and then drops back to idle speed. There is no smoke on start-up and there is not as much smoke at idle speed (although the exhaust gases do smell of smoke).I have tried doing some fault diagnosis myself and started by checking for play in the turbo compressor shaft and oil in the air inlet pipes from the turbo through the intercooler and the inlet plenum. There was very little play in the turbo and no oil whatsoever on the inlet side of the engine so, suspecting a turbo oil seal leak, I proceeded to look at the exhaust side of the turbo. Rather than disconnecting the exhaust downpipe from the turbo I undid the oxygen / lambda sensor blank on the downpipe and once again there was no sign of oil whatsoever. The next step was to do a compression check of the engine which resulted in readings of @ 135psi across all 4 cylinders. These appear a bit on the low side but are even and are probably correct as the engine is fitted with low compression pistons to enable it to run 35 psi of boost. My final check was to run the engine with the oil filler cap off and this revealed the fact that there was no back pressure whatsoever.The engine is a Cosworth YB200 long stud block fitted and, amongst many other things, is fitted with with accralite custom dish pistons, GT30 roller bearing turbo with TIAL external wastegate, BD16 inlet cams, BD10 exhaust cams etc, Bailey breather system. The engine runs and idles smoothly, and performed well on the rolling road, but seems to have developed the problem ever since. I am at a loss where to start looking next so any suggestions would be welcome. Thanks in advance,Danny.

jessie_rs

Could be the turbo oil seals have failed?

VEEDUBBED

Is there an oil restrictor fitted on the turbo's oil inlet line?

dannytattersall

Thanks for the replies. There is an oil restrictor fitted to the oil feed pipeline and it worked fine before the rolling road session. Regarding the turbo oil seals failing – would I be correct in assuming that this would be visible in either the inlet side of the engine or, more likely, in the exhaust downpipe immediately after the turbo? If so there is no oil in either of these.Regards,Danny.