Leon Speed

Basically a borescope is a camera on a flexible tube. It allows you to see inside the cylinder if the head is small enough to fit through the spark plug opening and if the head is lighted. There is a large variety in quality of borescopes, so obviously a good quality borescope allows you to see more than a lesser one. Also, cheaper borescopes are moved around by hand, professional borescopes are operated by some sort of joy stick. Some borescopes allow you to put a little grabber at the end to pick up small parts. Anyway, if you can lend one, that would be great. Just make sure the head fits through the spark plug opening and it is lighted. It would also help to provide a better/closer look inside the intake ports and valves.

jeff spahn

I had some crap on my valves also when I did my intake refresh even though I cleaned stuff out diligently. I vac'd stuff out as much as possible. Called it good. No problems now after the intake refresh other than leaky O rings which are unrelated to this.

Tony

after having a small washer drop by a rag unknown to me, i will never trust rags again. I'm just glad i took the 5 mins to hook up socket and turn the motor over by hand after working on it. The small washer just HAPPENED to drop into the cyl with the open intake valve.....the washer just happened to be steel....the washer just happened to fit through the spark plug hole on the way out....and now the washer just happens to be screwed to the wall on my tool bench, displayed like a trophy!
I still get quuuuuuezy thinking about the WHAT IF!!

I use aluminum speed tape now or better yet get the metal covers that DR sells!

928mac

OK if you have some dirt (not blast sand) that you missed and you want to remove it from the cylinder or valve, here is what you do.

Short of removing engine and head and washing it all.

Have you see or heard of a leak down test where you run compressed air down the spark plug hole?
If the valve is open, like you say, and you see some stuff on it, then pour some varsol (1/4 cup) down the plug hole.
Connect an air line with the correct spark plug air line adaptor, make sure to lay a towel over the intake port where the air will come out of, and give it full shop pressure 100-120psi.
The towel and dirt will shoot over the fender so if you do not want varsol on the car you best cover it. Blast it a few more times to dry it and it should look good.


Short of this the heads need to come off or you risk scoring the cylinders when the grit embeds on the side of the piston or rings and sorry but it may already be sitting there.
There is no way to remove it from around the piston except with a air nozzle when the heads are off.

It is a personal choice what you do. Good luck and what ever you decide, do it and don't look back. You wont blow up the engine if you miss some but the life of the cylinders may only go 300,000 rather then 400,000
Brad

Fortuna

You can follow any responses to give me advice. What Borescope better choice for the engine 928?

velocipus

Thank you Brad. That is very helpful. Unfortunately we cannot buy Varsol in California. Any idea if mineral spirit would be a suitable substitute? Brake cleaner maybe. I am guessing that it would be best to use something that will not leave a residue.

928mac

any kind of paint thinner or even isopropyl alcohol which is cheep and will not leave a residue.

You may be able to borrow an adaptor or phone any local tool supply.
I assume you have a compressor at home.

If you are unsure what to do.
walk into the back of your local shop (anyone) and ask any of the tech's if they would be willing to make a few bucks after work. Tell them what you need and they will bring the adaptor and line attached to it.

I take my tires to the back door after hours and get them mounted for $50 which is 1/3 the price around here.
They are always willing to make some extra cash

dr bob

The compression tester I use has a short hose with quick-disconnect air fittings on it for the gauge. It's suitable for thise exercise for sure. Look at the local prts store for a similar one, less than $25 and easier than trying to piece one together.

Varsol is not available here in Cali, but you can use paint thinner with some acetone blended in and get a similar result. It needs to stay liquid long enough to carry the crud out, but flash off when it's done. Be sure to cover the downstream spray path so this stuff doen't get on paint or other things, it will be a mess. It's also flammable, particularly an issue when you disperse a mist of it with the compressed air. Use a towel a few inches from the port to catch as much as you can, but don't block the port with the rag to the point where it reduces airflow.

velocipus

I have two compression testers that screw into spark plug hole. I will sacrifice one of them for this exercise (assuming at least one of them are the same diameter/ thread pitch as the 928.) I'm going to pick up some acetone (and penetrol for another project... can no longer get that in California either!) this afternoon. My girlfriend had an idea of setting up a vented spray recovery box so the thinner doesn't go everywhere.

dr bob

It won't be that big of a spray. Put an old bath towel over the intake area and it will do fine. Reality is that you can't pass that many CFM through a 1/4" hose into the spark plug opening. The initial liquid spray is surprising but only lasts a few seconds. Then it's a fog, and you really want to contain both so they don't damage anything and don't catch fire.

Do this outside if you can, away from the water heater pilot light, the air compressor motor (should be outside away from the car), etc. The fumes are initially heavier than air. Acetone burns with a relatively cold almost invisible flame. Inhalation of the flame is fatal, in case you were thinking of doing any circus stunts. Spraying it around increases the possibility of a flash/explosion if the aerosol is ignited. Bottom line: Be Careful!

928mac

What do the mechanic shops use over there in their parts washers (varsol tanks)?

velocipus

It runs! A bit rough (vacuum leak, plug wire...) Whatever it is, I will deal with it later. I can sleep easy now knowing that it starts and runs.

I wound up blowing compressed air through the cylinder for an entire day. Once I was convinced that I could get nothing else out of that cylinder, I bolted everything back together and VROOM!

Thank you all for all of your help. I'm excited knowing that I am so close to driving the Shark again!

Leon Speed

Great! Good for you.

velocipus

Now purring like a kitten/ roaring like a lion.

I am just a few procedures away from a road test. Bleed clutch/ brakes, hook up alternator vent, flush cooling system and wash off a year's worth of dust. Maybe a shakedown drive to Berryessa and back.
Once I feel good about the work I've done, then onto Porken S300 chip install and then I'm done... except for addressing sloppy shifter AND slow sunroof AND diff fluid leak AND paint AND... never ends does it.
It looks like I may make it for Sharks in the Park this year afterall

Bill Ball

Great! See you there. Let me know if you need any help with your remaining tasks.