Wednesday, 23 May 2007

Top end problems with 't Kreng

As the engine in 't Kreng has by now covered almost 85.000 km since it's restoration it was time to check the valve clearances again. Last time I checked them was in the summer of 2005, before the 10CR. As some off the clearances were just within the limit than, it was a safe bet to presume that had to adjust the clearances this time. This was also prompted by the start off a slight top end rattle. Nothing really worrying yet but it was there!

Measuring the clearances showed that they were between   0.10 to + 0.05 mm out, so they needed to be re shimmed. On a Sprint engine this means you first drain the coolant from the engine. This to prevent coolant from entering places it shouldn't, because you have to undo half off the head studs to get the cam and rocker shaft out to access the shims.
And of course there is the ever present risk of the sprocket to cam shaft bolts falling into the engine. To prevent this I always use a strong magnet to catch the bolts, together with a thick cloth stashed in the opening in front of the cam sprocket as second defence line, just in case!

However after removing the camshaft and rocker gear I discovered some rather nasty damage on the number 3 cam lobe, tappet and rocker.

Some slight pitting on the left hand side off the cam lobe;

A tappet that is fit for the bin;

And some rather uneven wear on the rocker face;

As I want to use the car for La Carrera Caledonia next week, something had to be done. As I had a new spare camshaft lying in the attic, the only things I needed was another tappet and rocker.  So off to RenĂ© last Sunday afternoon to have a look at the internals off my spare Sprint engine. The tappets in this engine were all fine but some off the rockers also had uneven wear marks on them. Luckily there was one in the engine that was more than good enough to use in the car.

So last Monday I could start with rebuilding the head. But because I was putting a new camshaft in I first had to put it in together with the rockers to recheck the valve clearances. It turned out the there was a slight difference between the two. After calculating the required shim thickness it was only a matter of searching for the right shims and put everything back in ... But despite having the complete stock off an (ex) Leyland garage on loan, I missed 5 shims. A quick phone call to a local engine rebuilder told me they had the required shims in stock : ). They also thought it possible to regrind the faces off the rockers, so I'll bring some over to them within the next few weeks, to see what they can do.

From then on it was all rather straightforward, clean thoroughly, reassemble everything using lots off cam lube, re torque the head, let the sealant dry for 24 hours and put new coolant in. After that I let the engine run for some 20 minutes @ 2000 rpm to bed the camshaft in. At first it was a bit noisy but that quickly settled down to normal proportions. Also the temperature, after reaching its normal value, remained steady.

As the engine was nicely on temperature I thought it a good idea to wire up the strobe light to check the ignition timing. But while connecting the light up I heard a rather funny noise. When I looked in the direction were the noise was coming from (thermostat cover) I saw a nice little (± 1,00 meter high) coolant fountain coming from the top coolant hose;

As you can see the hose is ripped cleanly open along both sides off the hose clip. OK better now than during Le Carrera Caledonia next week, but at this rate I am going through my spare parts rather quickly!

Luckily I still have a few spare parts lying around but I think it's time I go looking for some fancy silicon hoses for on the cars.

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