Oil jet cleaning

[Hedd_Jones]

another one here who has seen many steel plugs. The case for the engine I'm currently messing with has all steel plugs

I've also never needed to clean a jet, or known father to have ever done so. But all the engines were rebuilt and cleaned. Then used with 'classic' multigrade motor oil.

The engine im messing with is a 'used' one ex ebay. It is disgusting inside in places (there was no gauze in it). And some repairs (inc one by me LOL!) are questionable. IF all is well when I get it to run, its going to get a lot of oil changes at very low miles. So I can see why a jet might block. There was a horrible gritty black residue on the lip that the gauze bolts to.

[Mike Costigan]

another one here who has seen many steel plugs. The case for the engine I'm currently messing with has all steel plugs

I've also never needed to clean a jet, or known father to have ever done so. But all the engines were rebuilt and cleaned. Then used with 'classic' multigrade motor oil.

The engine im messing with is a 'used' one ex ebay. It is disgusting inside in places (there was no gauze in it). And some repairs (inc one by me LOL!) are questionable. IF all is well when I get it to run, its going to get a lot of oil changes at very low miles. So I can see why a jet might block. There was a horrible gritty black residue on the lip that the gauze bolts to.

Sixty years ago jet-cleaning was a roadside occupation on most journeys! I suppose we never used to do a thorough clean when rebuilding engines, and the oils used were just starting to have detergent additives...

[Ian Dunford]

Like Mike I am astonished to hear that some people have never had to clean their oil jets.
They must be either very lucky,or drive very few mileages.
Admittedly I don’t have to clean them as often as I used to,but not that long ago it seemed likely that a good clean was needed fairly regularly.
At least a couple of times a year.

[Tony Press]

another one here who has seen many steel plugs. The case for the engine I'm currently messing with has all steel plugs

I stand corrected 

Two brass or steel hex head screws on the offside of the crankcase along from the oil gauge take off - unscrew each carefully after wiping the area clean and use a straightened paper clip (leave a loop to stop it dropping through) to clear the jets which are just under the screws.

Also make sure you use a small paper clip- the larger one may jam in the jet 

[Hedd_Jones]

It seems this engine I've just installed has a blocked jet. 

I've done quite a few runs of 6 or 7 miles and got the engine hot enough to register where I would expect it to be on the wilmott breeden, but oil pressure is still over 10psi cruising and 7 or 8 at idle. 

I've tried a paperclip, which was fine for the front one. But the back one seems to be solid. 

Any ideas? short of knocking out the jet and replacing it via the sump.

[Reckless Rat]

Try a set of gas welder's prickers?

[JohnD]

I had to clean mine last week. I had the car out for a drive, and i had only made it to the road end when i heard a dreadful screach and the engine locked up, so i was towed home, stripped the gearbox off thinking it was that or the flywheel/clutch - but no, by thistime the engine was turning over again. so putgearbox back on, and then started it up, by time i drove from inside to outside of the garage it done it again. Lucky my mate was here who diagnosed it as lack of oil in the bores, so plugs out, oil down the bores and it turned freely. I then cleaned the Oil lets with a length of 0.6 Mig Welding Wire. Started it up and left it to tick over for 5min, then a short test dive and all seemed well.

The weekend past i done around 40- 50miles of up and down hill driving and it ran faultlessly

[Hedd_Jones]

thankfully it runs nice, no knocking. Just the oil pressure is too high. 

Ive found some small drills. I shall attack it with one of those next as the are less flexible than the wire ive used so far.

[Hedd_Jones]

I had difficulty unblocking my jets with any sort of wire also a paperclip, though with perseverance the paperclip got the front one clear. I decided something a little more stout was needed. 

I did toy with the idea of a small drill bit, but I was concerned about dropping it through. So using a spare engine I found a small allen key of suitable diameter, long enough to pass through the jet, but short enough so that it could be manoeuvred in under the water manifold.

With some moderate pressure from my thumb I got it through. When removed the muck was evident, thick black (and unfortunatley) gritty oil, much like the oil all over my steam engine ends up like. Yuk.

A 3 or 4 mile run confirmed this reduced the oil pressure to expected levels.


  jet.jpg (Size: 69.98 KB / Downloads: 113)

Personally I believe this demonstrates the robustness of the Austin design, I've driven the car at least 30 miles like this since the transplant, with one single round trip of 20. The oil pressure was high from day 1, but it took that long run to convince me all was not well. So its done all those miles with sub standard lubrication.

It also demonstrates the soundness of using modern multigrade oil with some detergent. The other engines here rebuilt in farirly modern times, run on detergent oil, with regular changes are immaculate inside and seem to be long lived. Never any need to clean the jets. 

This engine, which has clearly been knocking round for some considerable time, probably last rebuilt in antiquity (it has split pins in the big end nuts) was disgusting inside, was probably run on straight 30 all its life. And I guess cleaning the jets was a regular occurrence.

Can any of you who still run your cars on straight 30 confirm if you have to clean jets?

[JonE]

Good call on the pre-bent Allen key. Are you still running this on straight 30, or are you inferring that you have changed to start to loosen things? I'm imagining not.