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CATEGORY LISTINGS > MAINTENANCE / SERVICE > Glazing of cylinders

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Thread Title:

Glazing of cylinders

Created On Monday August 12, 2002 12:22

RobBurns

Posts: 1
Joined: Aug 2002

Monday August 12, 2002 12:22

I have a motor cruiser with two Volvo Pnta diesels, each 240hp. They had 750 hours useage when I bought and the boat had ben used only in canals with speed limits. As a result, the engines were run at about 1800 revs. The max revs are 3800. There is now oil coming from the crankcase breather, not in largs quantities, but enough to stain the bilges. I am tols this is evidence of glazing of the cylinders due to many hours running at low revs. It has been suggested that the cylinder head is removed to allow the cylinders to be scraped. The alternative is to remove the engine from the boat, a very expensive option. What is the danger from glazing? Can this cause catastrophic engine failure? Any advice as to next move?

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petelobus

Posts: 2
Joined: Aug 2002

Sunday August 18, 2002 17:13

Not had any experience of glazing with Volvos, but some with modern Listers in same condition. Worst that seems to happen is excessive oil consumption, which is ok if you dont run out of oil! Fix which used sometimes to work with the Lister was to fill with low grade oil (CC grade max) or running in oil, tie boat firmly to bank and run engines in gear for several hours at maximum speed obtainable without black smoke. Other rumoured fix that I was never brave enough to try was teaspoon of abrasive cleaner (Vim over here) down intake, after filter. Try this at own risk!
Contact me at petelobus@lycos.co.uk if you wish.

Ian

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RADAR

Posts: 5
Joined: Aug 2002

Friday August 30, 2002 17:40

Hi Rob,

I have ran volvo industrial engines (some used in marine) for many years and found that Volvos that are running light pass a lot of oil whether through exhaust manifold and/or turbo and so tend to drip and are always dripping from the breather pipe when working, whether its old or new some more than others, to be honest I have had my fair share of heads off volvos and bore glazing is always present its the norm but I wouldnt go to the expense of pulling apart as I cannot see what you are going to achieve, unless the engine is worn to excess and the oil is excessive thats leaking out the pipe , a simple manometer with a plastic tube filled with coloured water and a simple inch scale or metric and one end plumbed into your dipstick filler to carry out a simple crankcase positive or negative pressure, I let mine go to 1 and half inches positive before I pull apart or remove cam followers to check wear/ break up. my engines are abused from day one , sad to say but I have no control when on site hires.

If the oil can be caught in a container or pipe rerouted back into air intake ducking so its recirculating (positive crankcase ventilation- as all vehicles now conform to) may stop your staining ?????

Happy Cruising

CU
RADAR

-------------------------
I design and build from scrap parts high pressure centrifugal water pumps for the mining and chemical industries driven by a vast range of diesel engines that have been scrapped or have been retired due to current noise and safety standards and I containerise and acoustic as required.

Its a salvage squad hobby/living.

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thunderroaddrayage

Posts: 14
Joined: Sep 2002

Monday September 02, 2002 13:13

Most any diesel engine will glaze the cylinder walls if they are run excessivly at low R.P.M.s or idle.Youre best hope is what was allready mentioned.Fill the crankcase with light oil,run it under a heavy load and hope.Keep a sharp eye on youre temperature gauges while attempting this.Basically what youre trying to do is use the increased friction of the piston rings running in light oil to generate heat and dissapate the glaze.The glaze is just unburned fuel and oil deposits burned onto the cylinder walls by the higher combustion heat generated at low R.P.M.s when the cylinder is scavenging exhaust gases less eficeintly due to lower port velocity.The glaze fills in the cross hatch pattern on the cylinders from when they were honed during production and the piston rings no longer seal.The only sure way to remove glaze is to rehone the cylinders after wiping them down with a good degreaser like sray can either.Either makes a much better degreaser than it does a starting agent.re-honing would be expensive because the pistons must be removed.You would be one step away from a rebuild.Some people have had good results in de-glazing highway engines by using "marvel mystery oil".Yes,thats really the name of it.It is availible at any auto parts store here in new england,but a good parts man should be able to track it down for you worldwide.They might have a web site.For trucks it goes like this.Fil the crankcase up with 50% marvel,50% new oil,and install new filters.Hook it onto a loaded trailer,drive it one to one and a half hours at full throttle(use a lower gear in the transmission if neccessary to stay at the speed limit),turn around and drive back the same way.Drain immediatly while still warm(not hot enough to burn you).refill and replace filters.Substitute one gallon of marvel for one gallon of normally used oil.Drive normally there after.The theory is that the initial use of the marvel breaks the face of the glaze and softens it.Using a gallon of marvel on every change after continues to chip away at it.Marvel is a light oil most commonly used as a penetrating oil with excellent results.As for de-glazing,I've seen it work for some,not for others.Youre problem doesnt sound that severe,so who knows.To make a simple positive crankcase ventilation system,remove youre breathers from youre valve covers(if thats were they are).Look at the mounting style,grommett mount push ins,gasket mount twist ins,ect,ect.Go to A large automotive parts store.Look at what they have availible for cars and pickups with gas engines that had valve cover breathers that had hose nipples on them to route a rubber hose up to the base of the air filter housing.This was the earliest emmisions system,early to mid 70's.Dodge&plymouth used several styles and sizes like this.You will need a cooperative counter man who wont mind you opening lots of boxes.Once you find the right ones,then you need a couple of hose bungs that will take the same size hose as the breathers.Install them in youre intake tubing,hook up two peices of rubber line,and youre ready to go.A p.v.c. not only takes care of oil vapor,but it actually promotes better ring sealing,so this might also help with youre glaze problem beyond just cleaning up the mess.Hope this helps.

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morton37

Posts: 3
Joined: Oct 2002

Wednesday October 09, 2002 16:06

I supply Diesel & Petrol Fuel & Engine Additives/Treatments which promote a more efficient burn within the piston chambers, reducing unburnt fuel discharging thro the exhaust system. The engine treatments remove all carbon and sludge from metal components within the engine and can reduce exhaust blow pass, the cleaning agents and the MFM in the additives/treatments will remove the glazing without physically working on the engine.
My web site; www.italubricants.co.uk The products are not expensive and should help reduce significantly the back pressure.

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seahorse

Posts: 5
Joined: Nov 2002

Saturday November 30, 2002 22:44
we have found that the fitting of an in line good quality Magnetic Fuel Conditioner will solve glazing of the cylinder bores.........call me for one if it if it solves your problem pay me for it...peter simpson ,Simpson Engineering. +44 (0) 1653 696582

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