Follow on form this thread

http://www.300zx.co.uk/forums/showthread.php?t=141126

 

So a seized cam and a stripped cambelt can spell disaster but having faith in the robustness of the zed engine can often be rewarding.

 

The zed was recovered to us from another garage that had partial stripped the engine, mainly the radiator and cambelt covers which had revealed a destroyed cam belt and a seized right hand exhaust camshaft and of course the remaining cams and crank all wrongly timed.

 

 

Removal of the plenum, upper and lower injector assemblies, the timing sprockets with back plates and both of the camshaft (rocker) covers reveal the camshafts.

 

 

 

With the cam bearing caps and the camshaft itself removed the damage was clear to see, the camshaft front camshaft bearing, cap and head location bearing were mashed! and with a completely blocked oil way to that journal it was no surprise, in fact they amount of black sludge in there was no doubt part of the problem.

 

 

 

So before any more time and cash was poured into either replacing or repairing the engine we needed to see where we stood damage wise.

 

So by loosing the camshaft up enough to stay in place but now rotate albeit not very smoothly the engine was re-timed and an old cambelt fitted on. We then turned the engine by hand and noted that all of the lifters were operational and no sign of any tightness when rotating, and by the use of a camera scope no internal damage was evident,a compression tester was used for tdc checking and finally a leak test supported what we already thought from the beginning .... the engine was repairable.

 

 

So the strip begins, removal of the exhaust, n/s turbo, n/s exhaust manifold and with the plenum and front already stripped it just left the head to be removed, this now gave us conclusive proof that no cylinder or piston damage had occured.

 

 

With a replacement head complete with cams and lifters prepared , it was a case of rebuilding the engine, whilst this was done it made sense to do an egr valve removal and a plenum water by-pass.

 

 

The build up of course included a new timing belts inlet hose thermostat etc. once the covers were all on and the exhaust refitted an oil and filter change was done, the oil return pipe removed from the n/s turbo and the engine turned over until a steady return oil feed came out.

 

 

 

So there you have it all built up with new fluids both oil and coolant replenished it was time to start up, and it fired up almost immediately, a single injector connection required an extra clean and was soon firing on all six cylinders.

 

 

Well after the usual initial noisy lifters waiting for the oil to jack them up all went for a smooth settled tickover, warmed through and fully ConZulted the engine purrs and on a test drive pulls strong and smooth, one pesky lifter is doing its best to upset the day but sure it will quiet down once its had an extended drive.

 

So in essence what looked like a doomed engine brought back to life, this again reafirms what we know that this is one fine engine!

 

Oh and top marks to Jamie who performed 99% of the work with “Dad” holding the camera......nice one son!!

 

Jeff TT

Edited October 16, 201015 yr by JeffTT

great work both, and thanks for the write-up!! :bow:

great work both, and thanks for the write-up!! :bow:

 

Your welcome :D

 

Jeff

I think you should open up down on the south coast , !?

Cheers dad !!!!!!!!

Jeff you are a legend:thumbup: by the way I am buying a satnav:)

Great work there! Can imagine some other garages response.

Jeff you are a legend:thumbup: by the way I am buying a satnav:)

 

Cool, pm coming your way later!!

 

Jeff

Great work there! Can imagine some other garages response.

 

Oh yes:whistling:.

 

Jeff

so would this have been caused by lack of oil changing or crap oil? or just a heavy foot?

so would this have been caused by lack of oil changing or crap oil? or just a heavy foot?

 

Oil way blocked by black sludge, could be due in part to late oil changes, but most modern oils have properties to counter black sludge, so could just be bad luck, oil choice and long changes, not cause by heavy foot in any way.

 

Jeff TT

jeff and jamie i admire your knowledge, a very large percentage of garages would have given up and stated engine is dead. glad you sorted. i always like your threads on work stuff.very informative.

you are a credit to the club.

Oil way blocked by black sludge, could be due in part to late oil changes, but most modern oils have properties to counter black sludge, so could just be bad luck, oil choice and long changes, not cause by heavy foot in any way.

 

Jeff TT

 

as sussex stu says, these threads are always very interesting. keep them coming.

 

so would you say the repair (cost wise) was a economical one rather than just plonking another working engine in? i assume parts were low on cost to repair but labour must of been quite high?

as sussex stu says, these threads are always very interesting. keep them coming.

 

so would you say the repair (cost wise) was a economical one rather than just plonking another working engine in? i assume parts were low on cost to repair but labour must of been quite high?

 

Well can be a difficult one to call of course but in this case the saving got close to £700 over an engine change so based on that it was a good alternative route and took around the same time too.

 

Always happy to post the tech threads, good therapy for us too, its like a big debrief at the end of the job / week.:biggrin:

 

Jeff