Community Forums

Ruediger · 10-30-2021, 10:27 AM

Even after 18 months exporting my first class to germany, im learning myself into all details. With around 70k miles i have 0,6 liters oil consumption per 1000. thought, examining the pcv valve examining the first step before pulling the valve seals. And found a simple hose. The breather connecting the valve cover with the intake. Read this and that and am not sure, if this is original and, most important, should be exchanged against a pcv? Appreciate your suggestions.

Ruediger

donr103 · 10-30-2021, 10:45 AM

Hi.. from across the pond... 1st thing you need to do... is realise that Chevy light duty pickups engines and trans are the same ones used in rv.. you basically have a Chevy c2500 / c3500 Chevy pickup bolted to big frame with house on it.. so go online and get a repair book for Chevy c2500 same yr as your rv.. you are going to need it.. it's will have trouble shooting guide and engine specs..
That said.. if you post pictures better the ideas and opinions expressed here..
All you need to check pvc is just shake it... if rattles then it's ok.. you can clean it in diesel or carb cleaner until it rattled..
I think that is too high of oil consumption... but those engines will goes a long while.. burning oil.. only problem is they pollute.. not good.. valve seals may work.. but I think you might find.. you have more work than just that..
I would get a base line sniffer test.. look at results then you can measure the change in emission as you make improvements.. your local shop should have a sniffer..
Good luck and let us know what you did and maybe better members then me will help you

donr103 · 10-30-2021, 10:47 AM

Oh.. please post yr and make of chassis and coach..

Skip426 · 10-30-2021, 10:54 AM

Ruediger; some engines use a formed hose for the PCV system ( valve to intake ) others just a hose of the correct diameter and oil resistant compound ; that's available in bulk and purchased by length required .

Your engine may have come with a formed hose, and a previous owner replaced it with the bulk hose ; either works fine , you just need ; no leaks and hose that won't collapse under the vacuum..

EDIT: Keep the spark plugs in order as you remove them and examine them carefully , leaking valve seals will result in deposits on one side of the plug; from the direction of the intake valve in the combustion chamber.

Ruediger · 10-30-2021, 12:18 PM

Quote:

Originally Posted by donr103

Hi.. from across the pond... 1st thing you need to do... is realise that Chevy light duty pickups engines and trans are the same ones used in rv.. you basically have a Chevy c2500 / c3500 Chevy pickup bolted to big frame with house on it.. so go online and get a repair book for Chevy c2500 same yr as your rv.. you are going to need it.. it's will have trouble shooting guide and engine specs..
That said.. if you post pictures better the ideas and opinions expressed here..
All you need to check pvc is just shake it... if rattles then it's ok.. you can clean it in diesel or carb cleaner until it rattled..
I think that is too high of oil consumption... but those engines will goes a long while.. burning oil.. only problem is they pollute.. not good.. valve seals may work.. but I think you might find.. you have more work than just that..
I would get a base line sniffer test.. look at results then you can measure the change in emission as you make improvements.. your local shop should have a sniffer..
Good luck and let us know what you did and maybe better members then me will help you

Thanks, don. Dowloaded almost everything. And besides irv2, my homebase for adding up my knowledge. The class a a 2001 r-vision. 1320.

My pcv no valve inside. A simple hose. Thats why i was wondering, if a valve needed against blow backs etc. But the following post with that infos.

Oil consumption: i have light grey clous after firing up. Which i assume are the or at least one valve seals. Ive seen options changing them without pulling the head. Will do over the spanish winter. And def share my knowledge. My workhorse guideline saying, everything below one quart per 400 gallons, they dont call it a problem.

But i dont like it either.

Ruediger · 10-30-2021, 12:20 PM

Quote:

Originally Posted by Skip426

Ruediger; some engines use a formed hose for the PCV system ( valve to intake ) others just a hose of the correct diameter and oil resistant compound ; that's available in bulk and purchased by length required .

Your engine may have come with a formed hose, and a previous owner replaced it with the bulk hose ; either works fine , you just need ; no leaks and hose that won't collapse under the vacuum..

EDIT: Keep the spark plugs in order as you remove them and examine them carefully , leaking valve seals will result in deposits on one side of the plug; from the direction of the intake valve in the combustion chamber.

Skip, valuable update. Thanks a lot. The hose looks original. At least fitting tightly. I will pull the spakr plugs and follow your advice.

catmandoo62 · 10-30-2021, 09:15 PM

.6 litres per 1000 miles.thats a little over a pint per 1000 miles,big block chevies all use a little oil.i myself wouldn't worry about it.

RetiredBob · 10-31-2021, 05:35 AM

Quote:

Originally Posted by catmandoo62

.6 litres per 1000 miles.thats a little over a pint per 1000 miles,big block chevies all use a little oil.i myself wouldn't worry about it.

I agree. Both the 7.4L and 8.1L are known to burn as much as a quart every 1,000 miles.

exrench · 10-31-2021, 08:28 AM

My 8.1 has always used a litre of oil per 1800 miles. The consumption was slightly higher for the first 5000 miles and then settled down to the one litre per 1800 miles rate. I have had oil analysis done on an irregular basis with nothing terribly exciting to report.

yeloduster · 11-01-2021, 06:56 AM

GM's spec on oil usage for the 8.1L engine is maximum consumption 1qt/100 gallons of fuel. I think heavily loaded engines use more than lightly loaded engines.

If you have a motorhome with this engine and live where you rarely pull long grades and travel at speeds less than 65 MPG you may use no oil. I live in Colorado and drive the heck out of it. I use ~ 1 qt/1600 miles. That works out to about 1 qt/225 gal of gasoline. I'm happy with that!

My old 454 powered motorhome used about the same.

Ruediger · 11-02-2021, 06:13 AM

Quote:

Originally Posted by catmandoo62

.6 litres per 1000 miles.thats a little over a pint per 1000 miles,big block chevies all use a little oil.i myself wouldn't worry about it.

I was mixing metrics. Its now about 0.6 litres per 1000 km/ 650 miles. And im driving carefully. The question, what next besides monitoring: any limit from there i need to do the valve seals to be replaced? Anybody here in the forum who did this? Im worried about cat to be ruined with two much oil to be burned.

Daveinet · 11-02-2021, 07:01 AM

If your valve seals are shot, the oil will foul the plugs. Until that happens, don't worry about it. Yes, fix the PVC valve, but don't worry about the seals unless the plugs foul.

yeloduster · 11-02-2021, 07:49 AM

A puff of smoke when first started and when deaccelerating using the engine as a break are symptoms of valve seal leakage.

Using your numbers and converting to miles and gallons I get that your oil consumption is ~1 qt/1000 miles. At 7 miles to the gallon that would be ~1 qt/150 gallons. That is in spec BUT, if it were mine and it had visible smoke under deacceleration I would probably change the valve seals.

It isn't too hard. You need an adequate air compressor, an adapter so that you can apply air to each cylinder through the spark plug hole. To change the seals manually turn the engine so that both valves on the cylinder you are working on are closed. That would normally be Top Dead Center (TDC) on the compression stroke. Apply the air to that cylinder. This will keep the valves from falling into the cylinder. Now you can remove the keepers, the valve springs and change the seals.