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Mk IV, Superblower, CRS and other Continuation Cars Forum / MKIV Engine Problems
« on: June 14, 2019, 14:21:37 »
Hi, I'm not sure if anyone will be able to help, but all comments/suggestions gratefully received.
I'm also not particularly mechanically experienced so do bear with the description etc.
I have two concurrent problems with my MK IV (AK1259), whether they are related in any way, I'm not sure.
The car failed its recent MoT on CO output. I've had it to my local engine specialist to have the carb (4 barrel Holley 650 double pumper) cleaned / adjusted which is something it seems to need every couple of years. I understand this is due to the additives in higher octane fuels and the car getting very little use over the winter months. I've noticed over recent runs that the engine note is rather 'woofley' when cruising along in higher gears, in contrast to the previous 'bark' under acceleration.
On the rolling road we found output peaked at about 240bhp some 130/140 bhp less than peak achieved a few years ago and very unresponsive beyond about 3800/4000rpm.
Compression and leak down test of all 8 cylinders was good and within expected parameters. Plugs were okay. Slight oil leak from the rear of one of the rocker covers noted. The engine runs quietly with nothing giving concern in terms of 'noise'. This is also confirmed by microphone / headphone examination with the engine running at load. Engine man suggests this means it's unlikely to be a problem with cam lobes. Exhaust manifold downpipes not up to expected temperatures on a laser thermometer. Exhaust tested and no surprises there.
We've also discovered some issues with the wiring. This is causing concern with fuse holders melting and far too much current (17 Amps ?) on ignition circuit. Seems that it's wired through the ignition key and not routed through a relay.
Likely next steps will involve inlet manifold removal to inspect rockers / internals and possible partial re-wire. All sounding reassuringly expensive !
Has anyone experienced similar problems ?
Thanks.
I'm also not particularly mechanically experienced so do bear with the description etc.
I have two concurrent problems with my MK IV (AK1259), whether they are related in any way, I'm not sure.
The car failed its recent MoT on CO output. I've had it to my local engine specialist to have the carb (4 barrel Holley 650 double pumper) cleaned / adjusted which is something it seems to need every couple of years. I understand this is due to the additives in higher octane fuels and the car getting very little use over the winter months. I've noticed over recent runs that the engine note is rather 'woofley' when cruising along in higher gears, in contrast to the previous 'bark' under acceleration.
On the rolling road we found output peaked at about 240bhp some 130/140 bhp less than peak achieved a few years ago and very unresponsive beyond about 3800/4000rpm.
Compression and leak down test of all 8 cylinders was good and within expected parameters. Plugs were okay. Slight oil leak from the rear of one of the rocker covers noted. The engine runs quietly with nothing giving concern in terms of 'noise'. This is also confirmed by microphone / headphone examination with the engine running at load. Engine man suggests this means it's unlikely to be a problem with cam lobes. Exhaust manifold downpipes not up to expected temperatures on a laser thermometer. Exhaust tested and no surprises there.
We've also discovered some issues with the wiring. This is causing concern with fuse holders melting and far too much current (17 Amps ?) on ignition circuit. Seems that it's wired through the ignition key and not routed through a relay.
Likely next steps will involve inlet manifold removal to inspect rockers / internals and possible partial re-wire. All sounding reassuringly expensive !
Has anyone experienced similar problems ?
Thanks.