Help - sad tale of Mi16 spun bearing on #3 cylinder, 1000 miles after engine rebuild

[trashy 1]

A long story, but please bear with me!

 

History
In April I got my 205 mi16 back having had the engine rebuilt with:

 

• New rings
• Re-hone liners
• Valves - cleaned, re-lapped, new seals
• Crankshaft balanced
• New bearings
• Skimmed and pressure tested head
• Timing belt and pulleys
• Head gasket kit
• Deep cleaned
• New billet flywheel
• New oil pump and water pump

 

The engine has a diesel crankshaft, Wossner pistons, ARP rod bolts, Catcams camshaft , and Vernier pulleys. Jenvey throttle bodies, Emerald K6 ECU, oil cooler and baffled sump are also fitted.

 

Dyno
Having done 1000 miles since the rebuild, a few weeks ago I took the car to the dyno to get the map checked out.

 

The engine was warmed up and the map checked.

 

1st run showed 208BHP/154Nm (similar to figures when it was last on the dyno in 2011).

 

2nd run showed figures down a bit but 3rd run showed a big drop to 190BHP/135Nm.

 

Engine temps and pressures were normal throughout but after the 3rd run some breather gases could be seen coming from the engine breather and oil pressure was lower at idle then when the car arrived.

 

At this point it was decided to terminate the session pending further investigation.

 

Post Dyno
The car was towed back to the garage and the engine builder inspected the car when running.  I was told the car was ok to drive and to bring it over to his workshop for a leak down test.

 

Unfortunately the car cut out after 5 miles and now had a bottom end knock when started.

 

Inspection
On strip down it was found that the bolts were all torqued ok but that #3 cylinder had spun a bearing, damaging the rod and the crankshaft.

 

Fortunately the engine builder is going to stand by his build and rebuild it for me again FOC.  I'll be paying the costs for engine removal/refit and another dyno session (after perhaps 5000 miles this time).

 

Future
How do I minimise the risk of this happening again?  The engine builder suspects it might have got too hot on the dyno but accepts it could also be faulty parts.

 

Anyone know where I can get another diesel crankshaft if mine can't be reground?

 

Thanks for reading!
 

Edited June 19, 2019 by trashy

[petert 586]

Whilst you had new rod bolts, did you close and hone the rods? There were most likely oval.

[Thijs_Rallye 87 4 Cars]

Measure all crank journals and rod diameters, on roundness and dimension. And as Peter says, measure the rods whilst torqued up.

 

One thing which is mentionable, is that for the XU10J4RS on one crank journal the tightening is higher than the rest of them. I can imagine this has to do with lubrication issues for the rods. Since the RFS engines don not present the spinning bearing on rod no3 I suspect there is a link between these things.

[allanallen 528 2 Cars]

12 hours ago, petert said:

Whilst you had new rod bolts, did you close and hone the rods? There were most likely oval.

+1 for this

[DamirGTI 342]

I wonder if someone put the rod cap wrong way round ? .. or worse , mixed them between the rods .

 

Stripped few blocks which where poorly reassembled and thus needed machine work (crank regrind and re boring all 4 rods) , when people do not pay attention to mark the rod caps so that they're matching pair with the rods and mix them over in-between its always an mess with at best damaged crankshaft and bearings if not seized up engine and piston fly off the block .

 

D

[trashy 1]

Thanks everyone, much appreciated.

 

Would all of these suggested issues survive 1000 miles without any indication of a problem only to fail on the dyno?

 

 

[Andy 105 1 Cars]

A few queries. Is it an Xu10j4 engine or the RS version? . I assume that with Wossner pistons on o.e rods, the rods are crank centred with fully floating pistons. I also assume from your comments that the crank is damaged beyond repair ( ie a re grind) If so, I have an 88mm diesel crank . PM me if you need one . As for the failure, something amiss with the rod fit on the number three journal, as others have already mentioned .

 Best of luck with the rebuild.

 

[DamirGTI 342]

Back in the days , my mate done complete rebuild to OE spec 1.9Mi16 (done by local mechanic) , all OE parts too minimum aftermarket parts , was expensive rebuild ..the engine clocked about 5/6000Kms (i think ?) when it went bust on track after few laps - piston/conrod No.3 flew out off the block .

 

Till then , all was good .. myself i had a spin in it too before that and was driving fine .

 

D

[trashy 1]

Thanks for the comments everyone, sharing your wealth of knowledge is really appreciated.

 

Andy - the crank is being inspected at the weekend, so hopefully I'll know then if a new crank is required.  Thanks for the offer.

 

All - is #3 piston/conrod a known weak point on these engines?

[trashy 1]

Sorry for my ignorance but how do i tell which mi16 engine I have?  For some reason I thought I had an XU9J4 but I've no idea where I got that information from as I can't see the engine code mentioned in any paperwork!

 

I've attached a few photos of the engine to hopefully help identify.

 

 

Edited June 20, 2019 by trashy

[Andy 105 1 Cars]

Ah. It is an XU9J4 Mi16. Right. New story. In this engine, the rods are piston centred. Check that the Wossner are indeed guiding the rods, as the crank journals will not be . Next, you have the diesel crank. Check that your builder got the correct thrust washers as the standard ones will not work correctly .