12 replies to this topic

[1275MIN]

Hi Guys, hope you have your technical heads on today!

I have just finished building an engine i stripped down. Its a turbo lump out of a metro. I have had the usal, re-honed, new rings, lightened flywheel, duplex timming chain. The problem started when i found out i could not get the piston rings for the pistons that i had, so i spoke to Ian at AvonBar and he said i could get the pistons machined to execpt the new rings, which i did. started putting the engine together, pistons went in ok fitted the crank, and then it got stiff. I ignored the problem (like a ) (This is the first engine i have built) and as every thing else went on it obviously got harder to rotate the engine! Now the engine is nearly finihed i can just about rotate the engine with a breaker bar on the pully hex nut! There is no way a starter motor could turn it over.

So i have execepted that i will have to take the box off the engine to sort it out. Im thinking down the lines of a bent crank or conrods, what do you guys rekon? The engine turned over fine before which makes me wonder if some thing happened at the engineers! Or is there something i could of put arond the wrong way? I no the conrods have be fitted a certain way round other they will foul on the block so i am suer its not this.

This was my engine i have built so didnt really no what to expect whn buildind in, so go easy on me!

Any thoughts would be great
Cheers
Paul

[Guess-Works.com]

looks like you're going to have to strip the engine back down, as for machining the pistons, it would have been cheaper, and probably safer to buy new pistons, of which there are many available.

I suspect what may have happened is a ring is binding or you have the wrong size shells in the mains or mig ends. That will soon bind the engine up. If a machinist has buggered you crank, then take it back and complain.

My tip is, if it don't look or feel right, then it probably isnt.

Make sure you oil everything very well when your putting it together

ps. Welcome, and it's not as bad as it could be, at least youve realised somethings amis before you tried to start it.

Edited by GuessWorks, 27 February 2005 - 07:56 PM.

[siggy]

Unlikely to be a ring as that would have shown up when you fitted them, unless you used a big hammer.

When building a motor you MUST check the rotation after each stage, even each cap.

Strip it and start again.

Siggy

[Pez]

I agree siggy.

Strip it and try again.

Check the bearings are in the correct position before tighten crank and con rods.

Good luck
:wink:

[TimS]

i start buitling from the crang, so if u strip it and just put the crank in, and spin it when torqued up then you should b able to tell if theres something wrong if it doesnt spin freely. The put one piston int at a time, torque up the cap and make sure its not too stiff, there should b some resistance but not stiff if you get me.

[1275MIN]

Thanks for all youe help lads! Will let you know the outcome!!

[Dan]

Did you plastigauge all the journals or did you just trust the engineer? How much crank end float did you have and are the thrust washers in correctly (if they're in the wrong way round you have a steel to steel situation in the centre main which is a bad thing). Are you certin the piston ring grooves are deep enough to allow the rings to close up enough? Did you measure the ring gaps before building?

[1275MIN]

Thanks lads, will let you no the out come of it when i find the problem if its not to imbarrising!

[Bluemini]

I had the same kind of problem once, I built the engine up checking it at every stage, then when i came to turn it over after fitting one of the pistons (with new rings) it was really stiff. After a methodic strip down I descoverred I had broken a ring putting the piston into the cylinder, it was ok the first few times I turned the engine over, then the broken bit managed to get jammed between another bit of ring and the cylinder.

Another problem could be that you have the wrong size bearings, also, did you lube everything up when you put it all together?? Cleanliness and plenty of oil are the key!

[Bluemini]

A moment of inspiration while having a bath...

I can bet I am right on this too - Did you put the big end caps on the right rods the right way round?

I made the same mistake and got 2 on the rong rods and when tightened down hand tight, the engine will turn over freely, but when torqued up it is very stiff to turn over. Reason being that rods and big end caps are matched and honed out as one unit. Getting them mixed up will make the 2 out of line and can cause a tight or loose fit.

[Boab]

Having a bath and thinking about 'rods'. I wonder :fear:

[Bluemini]

It was my 'big ends' that did it

[Boab]

Stop bragging