Idle Oil Pressure

[Binnacle-ZA]

So how is everyone?

 

I've had my Manta's engine overhauled. Now a lovely purring 2.0.

 

But... Oil pressure drops to nothing at idle, i.e. Idiot Light on and not registering on the original pressure gauge.

Thought it might be the pump gears, swapped for a spare (used) set I had squirreled away. New are impossible to find in South Africa.

 

The pump cover has no wear to speak of.

Also checked the relief valve (timing cover one) and it's correctly seated.

 

Pressure jumped from 2 to 3.5 while running with the other gears, but still drops to nothing at idle. Have upped the idle to about 1200 to get it just under 1. But this is obviously not right.

 

Any Ideas what could be causing this? My mechanic thinks the gears probably are still too worn and just have too much slop at idle.

 

All pressure numbers are taken from the original oil pressure gauge, which goes from 1 up to 5, I can't remember what the unit is off hand.

[Beaker]

If I remember correctly the Manta A series gauges were marked KPa - an abbreviation for KiloPascals or Killer Paranoia Apparatus perhaps?

I used to see from somewhere between 1 and 2 at idle when cold, to just over 3 at speed.

 

There is a system of oil pressure relief valves built in to the chain case, they bypass a blocked oil filter in theory. It might be worth checking they are still installed and perhaps swapping the filter over.

 

EDIT - seem to recall that wear on the oil pump cover plate and gasket thickness can have some influence too.

Edited December 5, 2014 by Beaker

[mantadoc]

If you use an oil pump cover gasket on an engine that should only have a smear of sealer pressure goes through the floor.

If you use no gasket on an engine that should have one you sheer the pin in the dizzy drive cog.

Try a capillary gauge to validate the pressure

[H-400]

Check the distance between the two (installed)pump gears. Max space is 0.20mm.

Engines from 1985 and younger have no gasket,if you are not sure try to turn the gear with a

long big screwdriver threw the gap of the distributer.

If you'r not sure (I think a 2.0liter engine is not original in a "A"Manta)I can give you the dimensions of the

two different types of pump-house.

If it has got to have a gasket, they are very thin, a to thick gasket makes you lose pressure.

(gonna look for the dimensions, hope my English is good enough. I'm Flemish)

[bigcliff]

H-400 your English is very good mate

[Autocrosser]

I've had this before many many moons ago. It was a split O ring on the pick up pipe and man did it take some finding!

[OPEL PARTS GREECE]

oil pump gears?

[Julian]

oil pump gears?

Are you saying you have these gears Anthony?

[OPEL PARTS GREECE]

Are you saying you have these gears Anthony?

Only the 646345 GEAR PUMP OIL DRIVING 78,5 STD 1,7-1,9-2,0N/S/E (You use it with the driven one 646560)

[H-400]

Sometimes you can find those gears hidden on a shelf with a lot of dust on it. I already seen them

on German web-sites, new but they want the old one's to recover the shaft.

About the gasket: The gears are for both pump-houses identical, it is the depth of the house that is different.

The "old" engines with gasket: the gears stick 0-0.1mm out the pumphouse.

The "new from '85" engines without gasket: the gears stick 0-0.065mm out the pumphouse.

[Binnacle-ZA]

Whew, that's more responses than i was expecting 

 

Will try to answer everything I can.

 

 

There is a system of oil pressure relief valves built in to the chain case, they bypass a blocked oil filter in theory. It might be worth checking they are still installed and perhaps swapping the filter over.

 

EDIT - seem to recall that wear on the oil pump cover plate and gasket thickness can have some influence too.

 

Filter is brand new (obviously after a rebuild), checked the relief valve in the timing cover and it was fine.

Pump cover has no wear to speak of, was machined flat a year or 2 (or perhaps 3) ago. Not many kms racked up in that time.  

 

If you use an oil pump cover gasket on an engine that should only have a smear of sealer pressure goes through the floor.

If you use no gasket on an engine that should have one you sheer the pin in the dizzy drive cog.


Try a capillary gauge to validate the pressure

Pressure is perfect above 1200 rpm. Has correct gasket.

Machie checked pressure with his proper gauge and confirmed all but no pressure at idle, and rising with the revs. I can't remember the actual numbers (too many things on the go at the moment.)

 

Check the distance between the two (installed)pump gears. Max space is 0.20mm.
Engines from 1985 and younger have no gasket,if you are not sure try to turn the gear with a
long big screwdriver threw the gap of the distributer.
If you'r not sure (I think a 2.0liter engine is not original in a "A"Manta)I can give you the dimensions of the
two different types of pump-house.
If it has got to have a gasket, they are very thin, a to thick gasket makes you lose pressure.
(gonna look for the dimensions, hope my English is good enough. I'm Flemish)

 

It's a '75 1.9 that has been rebored to 2.0 (I'll edit this info into the original post.) so does have the gasket, with a tiny amount of sealer.

 

Your English is excellent 

 

I've had this before many many moons ago. It was a split O ring on the pick up pipe and man did it take some finding!

Oh man will that be a pain. Can't imagine how you would have ever found that.

 

Sometimes you can find those gears hidden on a shelf with a lot of dust on it. I already seen them
on German web-sites, new but they want the old one's to recover the shaft.
About the gasket: The gears are for both pump-houses identical, it is the depth of the house that is different.
The "old" engines with gasket: the gears stick 0-0.1mm out the pumphouse.
The "new from '85" engines without gasket: the gears stick 0-0.065mm out the pumphouse.

 

Non of the major parts places have anything. Am actually going to have a try with GM South Africa, we kept using the CIHs in new cars (albeit the 2.2 and 3.0) right up to 1995. Unfortunately GMSA's parts dept. is notoriously unhelpful.

 

*EDIT*

ok, for what ever reason, I can't edit my original post. Just FYI, the engine is a bored 1.9.

 

*REVELATION*

Remembered a conversation I had with the Machie, the Timing Cover has SEVERAL CAST TIMING MARKS ON IT, this is a late model feature is it not? i.e. should NOT have the gasket fitted? I'm guessing this was fitted somewhere along the line by a PO. 

Edited December 6, 2014 by Binnacle-ZA

[mantadoc]

Oh man will that be a pain. Can't imagine how you would have ever found that.

No O ring on the pickup pipe on CIH. Paper gasket. Once in lasts forever.

[Autocrosser]

No O ring on the pickup pipe on CIH. Paper gasket. Once in lasts forever.

I stand corrected it must have been a split in the gasket. It was approx 25years ago!

Put an XE in, at least you can still get the parts to fix them

[mantadoc]

checked the relief valve in the timing cover and it was fine.

*REVELATION*

Remembered a conversation I had with the Machie, the Timing Cover has SEVERAL CAST TIMING MARKS ON IT, this is a late model feature is it not? i.e. should NOT have the gasket fitted? I'm guessing this was fitted somewhere along the line by a PO.

Also remember that engines with the oil pressure bypass valve in the timing cover don't need the pump rotor cover with one, which is the later style, so those two statements appear contradictory

[moodoo]

Hi,

 

Am just nearing the end of a 2.2 build (into what was an early 1.9 engine). As stated above, for those early engines, the max protrusion of the gears out of the housing is about 4 thou. Researching on opelgt.com, the advice was that your gasket should be about 3 thou thicker than the amount of protrusion you have. The standard gasket that I got in my bottom end set was way thicker than that, about 0.45mm if I remember right, so I cut my own from some 0.25mm paper (sorry for the mix of thou and mm, was just easier to remember the numbers that way!).

 

With that thinner gasket installed, I checked that the gears rotated freely, which they did. However at that point I chickened out and put the thicker one in anyway! I figured better to find I had a little low oil pressure on idle, than have too little clearance, and wreck something. Plenty of engines running with too much clearance, but not many running with too little. I may find I have to put in that thinner gasket, but at least it's a relatively easy job to do.

 

Correct about the oil pressure bypass valve too. My early engine has it all built into the timing case, which means my oil pump cover is just basically a flat plate with 6 holes in it.

 

Good luck!

Fin

[Binnacle-ZA]

Also remember that engines with the oil pressure bypass valve in the timing cover don't need the pump rotor cover with one, which is the later style, so those two statements appear contradictory

 

It took me a while to figure that out what you where getting at, damn this heatstroke... Nearly wrote something horribly sarcastic 

 

Mine has, what appears to me, a late model timing cover and a flat steel Oil Pump cover (with an etched "A" on it).

 

The valve in the timing cover is working (Machie said so at least).

 

Basically what I think happened is this; The PO had the timing cover replaced, for what ever reason, and it was replaced with a bare/stripped one from a later engine, they put in the old the gears and the relief valve, either because they didn't have fresh ones, or they knew that the timing cover relief valve in late models had been disabled in favour of the pump cover one.

 

I'll only be able to check protrusions etc, probably next week, hopefully this weekend. Have laid up the car until this gets sorted.

[mantadoc]

That's the thing I don't believe you get a late model timing cover with a relief valve. I believe that was the early version with the flat pump gears cover. Everything past mid / late 70s had the relief valve in the pump gears cover

[Binnacle-ZA]

It's still there, they just fitted a much heavier spring, so it never opens. Replace the spring with an earlier one, and bingo. At least this is what I have been lead to believe, I do stand to be corrected on this.

 

But yes, if it is a late one, it should actually have the valve in the pump cover

 

*EDIT*

Nevermind. Been doing some more reading. If it is a late model timing cover, there is no provision for a relief valve in the cover. You are Correct, doc.

 

No idea what I have then, I haven't ever seen a pic of a timing cover exactly like mine, has 4 (i think) cast ridges, 1 long, others shorter.

 

Will put a pic up and grab the part number when I can.

 

*MORE EDIT*

I should stop reading things now, I'm getting so many contradictions. Yes, later have the timing cover relief,it's just disabled. No, it doesn't have it at all.

 

 I have declared my brain to have "the dumbs" until further notice, ha ha ha.

 

PS. Thank you to everyone who has and is posting.

Edited December 8, 2014 by Binnacle-ZA

[mantadoc]

Well if you have a flat gear cover holding the pump gears in the timing cover must have a relief valve because without one cold start will blow the seal out of the oil filter. That should make it old style in which case you put a straight edge across the gears. If they are proud use a feeler between the straight edge and the case. If they are sunk in clean all the oil out and use a feeler between the gear and the straight edge and to work out whether you are going to use a gasket, how thick or not at all.

don't forget to prime the pump. If not done you can ruin the bearings before it will draw oil, then you have no pressure at idle for a different reason.

You have got the right pickup pipe going low enough into the sump / oil level / dipstick? (long shot)

[Binnacle-ZA]

Okay, here goes.

 

Checked the clearances as best I could (Could only find my old feeler gauges which I can only actually read about 3 of the feelers).

Gears protrude, almost imperceptibly, smallest feeler catches the gap, but can't actually get under the set-square.

 

There is some quite noticeable rotational play between the driving gear and the dizzy. Don't have the backlash as I couldn't read the feelers. 

 

Will be coming back to it once I find my good feelers.

 

Made a paper gasket for the time being (to lessen the gap), little gasket sealer and back on. Pressure now hovers at just under 1 kp/cm^2 at hot idle (about 1000 rpm).

 

Timing cover part number is 8 981 079. Only info I found on this was an old E-bay listing, seems it might be off a six cylinder. Don't know if this will make a difference.

 

Gonna take a look at the relief valve myself sometime this week.