Engine: T5/R Broke my T5 engine. Whoops.

[andrewc1267]

Originally Posted by Juular

I had been having some rather strange issues with my C70 T5. It started as being quite sluggish, then developed into a wild surge followed by extreme hesitation especially at wide open throttle.

I did an overhaul of the vacuum and ignition system with all new pipes, clamps, leads and distributor. This didn't really help but while doing that, I noticed that the turbo control solenoid wasn't clicking at all when I gave it 12v.

I replaced it with a known good one and fitted a boost gauge. It sorted the problem and it was reading a consistent 10psi max which sounds about right.

Until I floored it away from a roundabout and then heard the mother of all death rattles. This was literally the most toe curling sound I've heard from an engine.

Yeah, that ain't straight anymore!



That was #1 Conrod which as you can see has suffered the effects of detonation pretty badly.

I am not sure what happened, but I am guessing that the stuck turbo solenoid was failing to open the wastegate and so the boost pressure has been skyrocketing, causing fuel cutoff to occur.

I don't know why the symptoms started after the working solenoid was installed, but there you go.

I pulled the head and pistons.



Banana!



And here is what caused the bottom end noise.

The little end here :



Was hitting the counterweight here:



Thankfully that was the only damage. The car wasn't smoking or using oil so I decided to rebuild. Bear in mind I have never even seen inside an engine before, but at this point there is really nothing to lose!

The big ends were ok but a little scored, so I replaced them.





I bought a set of Maxpeedingrods Conrods. I haven't actually heard anything bad about these so seemed excellent value.



Block and head cleaned up.







Rebuild process.







I couldn't get a hold of the correct anaerobic sealant for the cam cover and oil pan. I took a gamble and used flange sealant loctite 5922 which is much cheaper and easier to get.





It's an engine.



So despite the much sucking of teeth and negativity I received (not on here!).. it runs again and runs well and I'm quite happy.



I did not change the main bearings or piston rings nor did I service the valves. I did change the oil pan O-rings. I used clean engine oil an every surface for assembly but no assembly lube. Total rebuild cost including some new tools and fluids was about £350.

It took me and a friend a day to dismantle and bag the engine. I spent an hour here and there cleaning up the engine parts while waiting on new bits. It took me a day by myself to reassemble and start the engine.

This is quite an easy engine to work on. Worst part of the job is the oil pan. If you are doing this, do yourself a favour and bend the subframe tab out of the way, take the dogbone mount off, and Jack the engine up onto the next bolt hole on the mount under the crankshaft.

Moral of the story, be very careful if you start having turbo pressure problems and fit a boost gauge if unsure! The stock Conrods evidently do not like detonation very much!

Great write up really please you got it sorted. You must really love the car I've been a technician for nearly 30 years and I have walked away from cars for less mainly because I spend all day fixing them don't want to spend any spare time doing it. The new rods look great by the way

[Wagon Sailor]

Inspiring!
Thank you.

[Goupil]

Good job ! Nice to see such a job tackled on a driveway

Might be a dumb question, but could the small amount of missing metal on the crankshaft cause balance issue ?

[Juular]

Theoretically yes, but it's as smooth as butter. I don't think crank balancing is a particularly accurate science from what I've read, so this tiny amount of metal is unlikely to make much difference.

[CNGBiFuel]

Well done. If you'd asked me what damage to expect bending a rod, I'd be thinking a rod thru' the block etc. And I'd be wrong.

Great job. £350 to do that lot too, good for you.

[CNGBiFuel]

Seems I've got a similar job to do soon. On a compression test, one pot reads low, and valves have gone on another. You got rods out by removing the sump. Mine will need rings at least.

Access is tight but it's definitely doable and still easier than dropping the subframe. You can jack the engine up on the driveshaft retaining collar and hang it off the upper engine mount bolt for extra access.

Can we ask you to share tips on how you did this. How did you keep everything clean, and what, in hindsight, you'd do differently?

[Juular]

Of course, ask away.

While working on the head surfaces I plugged passageways and cylinders with heavy duty paper towels. After I was done I attached some narrow engine vac hose to my vacuum cleaner nozzle using duct tape and cleaned every channel and bolt hole.

I used that on the crank journal oil feeds before fitting the big end bearings to pull through a tiny bit of oil and make sure they weren't blocked.

A few tips.

Jack up and hang the engine before undoing the sump. It's easier to jack up on the sump than anywhere else.

Bend the subframe tab blocking the oil pan right out of the way or cut it off.

Remove the gearbox dogbone mount as it gets in the way of the oil pan.

It easier to remove the head with the exhaust manifold still attached, just disconnect the turbo. Saves you a gasket too.

The lower 10mm bolt for the main coolant pipe into the back of the head is a real major pain. Disconnect all fuel line clamps and the turbo coolant rubber pipe to improve access considerably.

ATF makes an excellent parts cleaner.

Before starting for the first time fill up the oil filter to the brim with clean oil and turn the engine anticlockwise a few rotations. Pull the spark plugs and turn the key until the oil pressure light goes out. It will take a worryingly long time but it will eventually build pressure.

Bag and label everything. Photograph every step especially the orientation of components like distributor rotor etc. This is really important as lots of the bolts are very similar looking but have marginally different lengths or threads.

Also no need for a cam locking tool or a cam cover pulldown tool. Just refit the timing top cover, align the cams and then tighten the cover bolts using the robertyDIY method (on his head gasket video). Check the cam timing at each bolt tightening pass.

Adjustments to the cam positions are best done with small light taps rather than any pressure - they are tight and will jump many teeth if you try to turn them by hand.

If I remember anything else I'll post it.