Oil circulation...

TommoT · Post by **TommoT** » Sun Jan 28, 2007 11:02 pm

... a little advice is needed. After a long haul Lasse's 18S is up and running, sort of and hurrah! It starts readily, but oil does not return, even after two short runs, one of about 90 seconds and after a pause, 30 seconds, still no oil returning. Engine sounds ok, idles without any alarming noises. Quick check shows that rockerbox is full of oil, running down the pushrod tubes (inside!). Now I know this engine has been disassembled and completely dry, but it was oiled liberally during assembly, is it safe to go on or is more investigation needed? A total of 2 minutes without any sign of returning oil seems a lot? The pump end covers are not leaking and the feed and return lines show no signs of leakage.

itma · Post by **itma** » Sun Jan 28, 2007 11:32 pm

I`d chuck a cup of oil into the rockerbox first and leave it overnight.
did he prime the filter tunnel and filter with oil?
I have often used an oil can to squirt oil into the return pipe inside the tank if things seem a lttle slow, then you can at least see if theres anything being pushed out.
bearing in mind what a dogs breakfast he has,is there anything daft nothing daft like having a small oil pump guide pin in a later pump plunger with the wider groove?
metricated sump plug not so long as it obstructs the return hole in the casting?

Don Madden · Post by **Don Madden** » Sun Jan 28, 2007 11:40 pm

Also guide pin in guide properly. The relieved end goes in the guide first. The rear pump plate must seal airtight as it develops a vacuum for half the stroke before the inlet port is uncovered by the plunger. Were the spiders blown out of the return pipe before fitting? The drill way from the sump joins the one to the pump high in the case at an acute angle, which has been known to trap obstructions.
Cheers, Don.

Biscuit · Post by **Biscuit** » Sun Jan 28, 2007 11:41 pm

Remove the filter in the tank and peer down the 'ole with a torch, after two minutes there should be oil showing in the bottom, if no oil, run it for another minute, looking to see if oil appears, if none appears after this time you have problems.

TommoT · Post by **TommoT** » Mon Jan 29, 2007 11:04 pm

Thanks, everybody. Just had a peep down the filter tunnel and oil seems to begin to fill at the bottom. In this case we also had the problem with the filter element, where too much filter material was folded around the ends. A little trimming took care of that.

Guide pin for oil plunger is in and seated correctly, oilpump housing end plates seem to be tight, but this is an area, we will look into, in case oil doesn't start to return in the usual gulps!

But Ken, something starts to rustle in the back of my head, when you mention sump plug. The original sump plug hole has been welded up, and a new one cut just beside it, to make room for a, yes you guessed it, metric plug! I will check if this could cause blockage.

Otherwise oil lines are clear with new rubber cross overs, but we'll try and squirt some oil in where possible, prime the lines, and then see what happens.

Will report back!

Don Madden · Post by **Don Madden** » Tue Jan 30, 2007 12:00 am

Welding up the original sump drain plug hole can be a problem on long stroke engines as it gives access to the drillway that sucks up the return oil.

Cheers, Don.

itma · Post by **itma** » Tue Jan 30, 2007 9:32 pm

I once had a similar problem with that cast in oil line, it drove me nuts, a tiny piece of broken piston had got itself stuck just inside and acted like a flap valve

TommoT · Post by **TommoT** » Sun Mar 25, 2007 10:59 pm

...this problem seems like ages ago, but in the end it took 3 running sessions of about 90 seconds each, before we began to see oil coming out the return pipe. Scary! But it must be added, that this was a completely dry engine, apart from the oil we tried to pour into the rocker box and down the pushrod tubes and what was applied to moving parts during assembly. The felt oil filter in the oil tank was also fresh and bone dry, and this in particular seemed to soak up oil for ages before allowing any oil out of the return pipe. We took the filter out during the second running session, and discovered oil finding it's way to the bottom of the oil filter houseing. This calmed us down considerably!

Don Madden · Post by **Don Madden** » Mon Mar 26, 2007 2:25 am

A good reason not to start up the engine & filter dry. The plunger pump is a low volumn, low pressure type & circulates oil slowly.

It is, however, reliable & adequate for it's application if assembled correctly.

Cheers, Don.

crawsue · Post by **crawsue** » Wed Mar 28, 2007 8:25 pm

I suppose that I shouldn't read all these topics,as all it does is put doubt into my mind! Since getting my rebuilt G80s I have done about 250 fairly easy and trouble free miles,usually cruising around 50/55 mph with occasional bursts of 60ish.When peering into the oil tank my impression of the return flow is just a "trickle".My previous G5,on the other hand,appeared to have a much more energetic "spurt"!I realise that the combined oil-tank/crankcase setup of the G5 is totally different to the G80,but the shocking pictures recently posted of crank-pin /big-end bearing collapse in the Photos section has put the wind up me.Are Don's soothing words pertinent to my "flow"?---Worried of Glasgow.