Welcome to our BMW E30 based Marlin Sportster Build Site,
we hope you will find this documentation interesting and helpful.
It took 2.5 years and has now passed the SVA test, too see the Sportster out of the road have a look at one of the videos here.
After a very long wait for a new set of wish bones we're finally back on the road again! In the mean time we've used the garage time to rebuild the engine from a 2.5 to a 2.8 creating an M20B28 stroker engine. It uses the crankshaft from the later BMW M52B28 and the conrods from the M20B20. Not much more work is needed other than a clean up and slotting those bits together (a custom map is required but readily available in chip form from Ant @ A-Tech). To read the full engine rebuild click here
To read the whole build from the start click here.
06/05/2008
Stoneleigh - National Kit Car Show 2008
It was the Sportsters first year at Stoneleigh. It nearly didn't happen because of the weather. We set off around 10:30 in the rain getting to Stoneleigh some time after 12:00. It was good to meet up with the people from Madabout-kitcars and the Marlin Owners club.
Click here for 98 pictures from the show (starts at the bottom of the page)
04/05/2008
Fine tuning on the handling
Toe fine tuning after changing the wishbones before the trip to Stonelight:
Starting point, 1.25 degrees negative camber, castor set 3 washers on the front and 4 on the back.
Symptoms - car does not auto centre going forwards, but it does backwards. Problem is too much toe in.
1) Mark on the track rod a line so you know where the top is.
2) Unbolt and turn the track rod by 1 turn so it move out from the track rod end - this moves the wheels outwards at the front.
3) Take it for a quick drive forwards and back and see how it feels. Ours felt a bit more neutral going back ward but still no auto centre.
4) Repeat if needed, we did with a 1/2 turn. Now backwards wasn't auto centring much at all and forwards was doing it a bit, but not quite enough.
5) Repeat if need, we did an extra 1/4 turn. Now the auto centring forwards was very good. Still slightly loose around the middle but 1/4 turn and it runs nicely back into line.
This has a made a huge difference to the handling feel. It feels nimbler into the bends and is easier to steer.
I've also moved my seat a notch forwards which is less relaxed but gives me better control.
17/04/2008
Temp Sensor
The reason the temp sensor was not working is that the bigger bit at the end that does the sensing had fallen off! Doh.
New sensor from CBS looks a lot better. The switch has an override setting so if the sensor goes you can wind it all the way up and the fan comes on even when the engine is cold.
This is the new sensor: http://www.cbsonline.co.uk/adjustabl...stat-763-p.asp
Been for a 15 mile round trip an all is well again.
The Rad is a bit border line -situation is the temp comes up and keep going up until the fan kicks in when your stopped. The fan stops the temp going further but the rad is not big enough for the temp to come back down again to normal when sat in traffic.
So it will be OK for now, We'll see what it does when the outside temp goes up.
13/04/2008
Woohoo, runs again
Engine runs again 
Let the oil pressure come up on the starter again without plugs. It was tad rough to start with as it tends to be.
Turns out the fan temp sensor switch is broken which is why the fan wouldn't run when it was hot.
So the problems were dodgy earth, broken fan switch and the starter stayed engaged.
Solutions: New earth strap, new fan switch on order, greased starter mechanism, new oil, new filter.
I may need a new starter, the alternator could do with being replaced as well.
All in all lucky escape.
Once I have new bits we'll be able to take it for a run make sure it OK over a longer period.
12/04/2008
Diagnosis Part 3
Taken the water pump out, it looks fine. No damage or wear marks.
Also taken several main bearing caps off and check the shells. They all look OK slowly starting to wear off the protective layer - no obvious damage.
Next step is reassembly, new earth strap, new oil and a new filter. Fingers crossed it will run OK again.
10/04/2008
Diagnosis Part 2
On inspecting the sump it turns out the ring terminal for the earth strap has broken, it was in place so that you could not see it had broken. There was a bit of contact but not much. This is the cause of the high oil pressure. Not much earth gauge OK when you put it on ignition 2, run the starter and it screws that up so the pressure goes up. Disconnect it and no earth = gauge on highest setting.
The also means the starter does not run properly as it doesn't get enough power.
Took the sump off. No obvious marks in any of the bores from the bottom. Push in the oil return and the oil runs out fine, oil pump seems to be OK.
Added a temp earth strap and now the starter runs fine turning the engine over without any problems (no plugs) - no odd sounds from it either.
Hypothesis is airlock (driving up hill), overheat and then unable to run anything due to the earth strap.
Seizing probably due to small tolerances and overheat. Need to pull a cap off check a shell for damage.
Doesn't look as bad now as it did initially. I'm going to do have more of a look around, get a genuine water pump from BMW as the one I have makes a noise and a new sump gasket, new oil and filter and see how it goes.
09/04/2008
Diagnosis Part 1
Testing Round 1 (not much time):
I can hand crank it fairly easily now, it does seem to get a little notchy in places.
Also the starter can turn the engine over however I have to hand crank it a few time first.
I did noticed the oil pressure went really high after a few turns of the starter
Testing Round 2 (a bit more time):
Thermostat is fine, water pump seems to be pumping OK, but not pull it out yet (rad is in the way). Oil in the bottom was quite dark but not clumpy. Oil in the top was still quite light.
When you crank the engine on the starter a few seconds the oil pressure goes way way up - I stopped at 6 bar.
So me thinks there's a blockage somewhere. Not pulled the sump off yet, but that's the next step.
08/04/2008
Damn!
Was out for a drive today again as it was still sunny, unfortunately the engine over heated after 30 miles - only for a very short period of time maybe 30 second before I noticed. Let it cool but it seized up - balls.
Been towed home (not too far luckily) so this weekend will be take the engine to bits again time!
Took the plugs out and it is possible to turn it over so I'm hoping it's not too bad. Ran fine for 250 miles!
At least it still has 4 wheels this time 
03/04/2008
Fuel Tank Breather
The breather that comes with the kit may not be ideal for injected engines, the tank pressurises during use to a very high level. As it is only a one way valve it only let air in as you use up fuel. The other issue we've been having is when there's a slosh of fuel it lets out a waft of petrol which really is not very pleasant.
Out solution was to get a mocal two way valve and a positive shut off so air can get in and out. Additional when there's a slosh it doesn't leak petrol all over the place.
Fitted the mocal valve today brimmed the tank and went for a long drive - no more petrol small wafting through the car when accelerating hard or going up a hill!
30/03/2008
On the road again!
On the road again:
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