Volvo MD1 Rocker Shaft Oil Supply

[johnfhn]

I have just rebuilt my MD1 after replacing the Cyl Head Gasket and the engine is running OK except that insufficient oil is being fed to the rocker shaft, some oil is coming through the oil feed pipe but it seems not to have sufficent pressure to flow through the rocker shaft oilways, any ideas please?

 

[Bilgediver]

Did you kink the supply pipe when unbebnding and bending back to shape and so reduce the supply drastically?

Is any oil appearing in the rocker compartment from the rockers?

 

[johnfhn]

The supply pipe has not kinked. When I undo the banjo and hand crank the engine oil flows from the banjo but when I connect it up to the rocker shaft and crank or run the engine no oil is coming through from the rocker shaft assembly into the chamber. I have checked the rocker shaft as well and there does not appear to be any blockage.

 

[Bilgediver]

SOmetimes there is a low flow but usually something. The flow is dependant on the clearance of the rocker bushes and oil pressure. Maybe you have tight clearances and low pressure. Try and borrow a pressure gauge and screw it in where the oil pressure sensor goes. You should use a gauge with a range of about 0 -30 PSi

 

[VicS]

Do tell us was rotating the rocker shaft through 180° as suggested on the MarineEngine.com forum the answer to the problem?

 

[Bilgediver]

Do tell us was rotating the rocker shaft through 180° as suggested on the MarineEngine.com forum the answer to the problem?

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I can understand this answer if the oil feed was up the rocker shaft supports however it is fed in the end of the shaft....

Mind you in all the years I have never taken the shaft out of the pedestals as it is not necessary maybe an excuse to look at one this weekend.

 

[VicS]

[ QUOTE ]
I can understand this answer if the oil feed was up the rocker shaft supports however it is fed in the end of the shaft

[/ QUOTE ] Quite. I wondered if it was to do with the position of the hole feeding oil out. If the rockers are plain and the hole was on the underside of the shaft they would block off the flow maybe but if the rockers are bushed with a bearing with an oil groove all the way round like they are on the MD1B that wont apply.

Normally though if the position of the shaft was important it would be made so that it could only be fitted correctly wouldn't it?

 

[Bilgediver]

Normally though if the position of the shaft was important it would be made so that it could only be fitted correctly wouldn't it?

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One would think so... For most of the cycle the rocker arm is floating the shaft however for the open period of the valve it is lifted. Surely the oil pressure is enough to find its way to the bush no matter how?????

I still question the available oil pressure. MD engines are renowned for operating at low pressure.

 

[Bilgediver]

Looking at the workshop manual shows the oil hole at the 9 o clock position and no mention of this position in the text.

Manual

 

[johnfhn]

The problem did seem to be the way I had fitted the rocker shaft assembly, but the actual shaft does have a cut away through which one of the fixing bolts goes and it can't be fitted 180 degrees out, but after blowing through etc and refitting it is flowing through OK now and all is well and I'm sorry I can't be definitive on what the problem was but thanks everybody for your input.

 

[VicS]

Link for the manual is

http://privateer26.org/pdf/Volvo_MD1-D1-MD2-D2.pdf

That's the second URL I've corrected this morning!
Thanks for posting it though as it is one I did not know a link for.

Problem apparently now solved. The position of the hole is the same as in the MD1B I think. what i said about the effects of it being on the bottom was utter rubbish anyway!