Dexta oil pressure

[Nick]

Evening, I think I may either have a problem, or be worrying too much. Ive recently partially re-built my dexta engine, i.e I renewed the piston rings, lightly honed the bores (which are within limits), micro'd the crank (which as far as i am concerned is ok), renewed the bearings, and had the cylinder head overhauled with new valves/guides etc.
Now when i was taking the head off (before i re-built), i didnt see the small oil pipe going from the block to the head, so naturally i snapped it in half. Having now put back together the engine, i put some oil in it and decided to see if it turned over ok on the starter, which it did, with very good compression etc. Next i thought i would check if the oil light went out, but it didnt (only at cranking speed). Bearing in mind that it did before, naturally this had me worried.

But then i looked and id completely forgotten to replace the little oil pipe which i snapped! However there is no oil coming from the block where the pipe attaches, so really my question is, does this pipe need to be attached to get oil pressure up?

P.S : I cannot find another pipe on ebay etc, so im going to make one out of 3/16 copper pipe

PPS : Before i took it apart there must have been oil going up this pipe because there was oil on the rockers when turning over, so I know the pump is ok, and yes i replaced the oil filter, and yes im sure i got the oil pick up pipe in the right place

[Jerry Coles]

Nick
When I replaced my engine with a new block I was worried about oil pressure so I found a T adapter and fitted a guage and the switch to the block.
There is a thread about it somewhere.
If you want to borrow my T adapter and guage you are welcome to it. Just PM me and I'll pop it in the post.
On the Dexta engine the oil to the rocker shaft is metered by the oil feed to the camshaft from the lower part of the block just behind the timing cover.
This pipe goes up to the camshaft and when the camshaft centre bearing is aligned it has a slot machined in it which then lines up with the pipe going up to the head and rocker shaft.
You should be getting a squirt for very rotation of the camshaft.
Try loosening the pipe from the block up to the camshaft and see if your getting oil there as its a feed from the main oil gallery.
If you haven't got oil pressure there then look at the pump/strainer/filter path.
Regards
Jerry
Bath
UK

[Nick]

Hi Jerry, thank you for your reply. To be honest ive just thought, i may not of been giving the oil enough time to get up there, its just the fact that before it was taken apart, the oil light went out when i turned it over and now it doesnt.
I think im going to investigate more when i get home from work tommorow, and thank you ever so much for the offer of your guage, i will let you know if i need it.
I will keep you posted

[Nick]

Also I have just had a brainstorm, before, when it had no compression because of stuck piston rings, obviously it was spinning over faster so the oil pressure would of been greater

[russelm]

Having re-built my engine recently (although I have not yet started it) and having spun it over on the starter to check oil pressure I cna offer the following.

I was not convinced that the dexta oil pump would effectively self prime so I packed mine with Vaseline.

I also used an oil can to pump oil in through the pipe you mention to the cam area and repeated wth the lower pipe towards the main oil gallery.

This resulted in oil pressure coming up pretty quickly and oil appearing at the rockers pretty much straight away.

[llanfair]

Hi Nick
The problem you have is maybe that you have not turned the engine over for long enough to fill the the oil filter bowl with oil,
There will be no oil flo anywhere until this is full and the oil pressure relief valve opens.(don't panic)
Llanfair.

[Nick]

Well it seems i was indeed panicking too much, because i turned it over for longer this time. the oil light went out, and then i heard the pitter patter of oil in the strategically placed bucket, which is a relief.
Also it did start to smoke a bit out the exhaust (it didnt fire), however i havent got the diesel lines connected to the tank yet so providing i can get hold of a decent fuel tap/primer pump, it should run......
And when it does, i will post pictures of the project so far!

[Nick]

Wahoooo! IT RUNS! I was not expecting it to, it made me jump and of course all the spanners etc on the fuel tank went flying, i had shut the shed doors so i couldnt see for smoke! But, it runs, and very well at that, seems to hold water ok. I didnt have to use the glow plug (the primer is not working either) infact i had a small lawnmower fuel tank cable tied to the steering wheel with about half a gallon of diesel in it.
So im a happy boy, will get it out the shed tomorow and take some pictures and then try and put a progress report up