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Discussion Starter #1 (Edited)
Opel observed that early versions of its 1.9L engines were prone to a loss of
oil pressure which could result in damage to main and or connecting rod bearings
(a very bad situation!) caused by sticking of the early-design relief valve ball.

Opel soon issued a repair kit to retrofit these vulnerable early engines, and
installed it on all new engines from mid-1970 onwards, with a relief valve
relocated to the oil pump lower cover plate. "This redesigned and relocated
valve eliminates the possibility of the pressure relief valve sticking with a
resulting loss of oil pressure"
according to Opel. Opel also noted that improper
installation of this cover, which would negate the relief valve operation, "will
result in uncontrolled oil pressure" (which can blow seals and gaskets
such as the oil filter ring - another very bad situation!
).

This is important information for those who might consider retrofitting an Opel engine
with an oil pump cover which does not include this important relief valve!

Text and associated diagrams from the Opel Technical Bulletins which describe
these oil system topics are below:

Opel Technical Service Bulletin 69-T-04

To all Opel dealers

Subject:
Loss of Oil Pressure - Opels with 1.5 and 1.9 Liter Cam-In-head Engines

Condition:
Loss of oil pressure which can result in damage to main and/or connecting
rod bearings and crankshaft.

Cause:
Pressure relief valve ball sticking as a result of foreign material or sludge
build up in the timing chain cover bore.

Correction:
When loss of oil pressure is experienced, or the above condition is suspected,
the bypass valve plug and check valve ball should be removed and the
bore thoroughly cleansed with a suitable solvent to allow the ball to operate
freely.

Procedure:
On 1968 and 1969 Opels with A.I.R. system, it is necessary to remove the
A.I.R. pump for access to the bypass valve plug, It is not necessary to remove
the timing chain cover assembly.

1. Remove the bypass valve plug. See figure 1.
2. Remove the bypass valve check ball and clean the bore with a suitable
solvent. Make certain the check ball will operate freely in the bore. See Figure 2.
3. Reinstall the check ball, spring, washer, and plug.

Note:
It is important that engine maintenance schedules are followed and that the oil
is changed at least every two months or 3,000 miles, and the oil filter is changed
every second oil change.

Opel Technical Service Bulletin 70-T-05

To all Opel dealers

Subject:
Improved Oil Pump Pressure Relief Valve -
All Opels with 1.5 and 1.9 Liter Cam-In-head Engines (1968 through 1970)

A kit, part number 16-06-226, has been released to relocate the oil pump
pressure relief valve. This redesigned and relocated valve eliminates the
possibility of the pressure relief valve sticking with a resulting loss of oil pressure.

The kit consists of the following:

A - One (1) pressure relief valve assembly with pump cover.
B- Six (6) pump cover attaching screws.
C - One (1) pump cover gasket
D - One (1) reinforced spring.

Condition:
This kit is to be used whoever a loss of oil pressure or suspected loss of oil
pressure is experienced. It is also to be used when any major engine repairs
are made.

Procedure:
On 1968 and 1969 Opels with A.I.R. system, it is necessary to remove the AIR
pump for access to the bypass valve plug. It is not necessary to remove the timing
chain cover assembly.

1. Remove the bypass valve plug, spring, and bypass valve check ball.
Clean the bore with a suitable solvent. See Figure I, Item E.

2. Reinstall by pall valve check ball.

3. Install new heavier spring from kit (Figure II, Item D) and discard old spring
and reinstall bypass valve plug.

4. Remove existing oil pump cover. CAUTION: The oil pump gears are not
retained in the housing; care must be taken to remove the gears when the cover
is removed so that they will not be dropped and damaged.

5. Install the new oil pump cover with relief valve, new gasket, and screws
included in kit. See Figure II, Items A, B and C.

Note: The oil pump cover must be installed with relief valve plug to the rear of
engine as shown in Figure II. It is possible to install the cover with valve plug
to the front of the engine, which will result in uncontrolled oil pressure.

Opel Service Department
Buick Motor Division
Flint, Michigan
 

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Opeler
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Opel observed that early versions of its 1.9L engines were prone to a loss of
oil pressure which could result in damage to main and or connecting rod bearings
(a very bad situation!) caused by sticking of the early-design relief valve ball.

Opel soon issued a repair kit to retrofit these vulnerable early engines, and
installed it on all new engines from mid-1970 onwards, with a relief valve
relocated to the oil pump lower cover plate. "This redesigned and relocated
valve eliminates the possibility of the pressure relief valve sticking with a
resulting loss of oil pressure"
according to Opel. Opel also noted that improper
installation of this cover, which would negate the relief valve operation, "will
result in uncontrolled oil pressure" (which can blow seals and gaskets
such as the oil filter ring - another very bad situation!
).

This is important information for those who might consider retrofitting an Opel engine
with an oil pump cover which does not include this important relief valve!

Text and associated diagrams from the Opel Technical Bulletins which describe
these oil system topics are below:

Opel Technical Service Bulletin 69-T-04

To all Opel dealers

Subject:
Loss of Oil Pressure - Opels with 1.5 and 1.9 Liter Cam-In-head Engines

Condition:
Loss of oil pressure which can result in damage to main and/or connecting
rod bearings and crankshaft.

Cause:
Pressure relief valve ball sticking as a result of foreign material or sludge
build up in the timing chain cover bore.

Correction:
When loss of oil pressure is experienced, or the above condition is suspected,
the bypass valve plug and check valve ball should be removed and the
bore thoroughly cleansed with a suitable solvent to allow the ball to operate
freely.

Procedure:
On 1968 and 1969 Opels with A.I.R. system, it is necessary to remove the
A.I.R. pump for access to the bypass valve plug, It is not necessary to remove
the timing chain cover assembly.

1. Remove the bypass valve plug. See figure 1.
2. Remove the bypass valve check ball and clean the bore with a suitable
solvent. Make certain the check ball will operate freely in the bore. See Figure 2.
3. Reinstall the check ball, spring, washer, and plug.

Note:
It is important that engine maintenance schedules are followed and that the oil
is changed at least every two months or 3,000 miles, and the oil filter is changed
every second oil change.

Opel Technical Service Bulletin 70-T-05

To all Opel dealers

Subject:
Improved Oil Pump Pressure Relief Valve -
All Opels with 1.5 and 1.9 Liter Cam-In-head Engines (1968 through 1970)

A kit, part number 16-06-226, has been released to relocate the oil pump
pressure relief valve. This redesigned and relocated valve eliminates the
possibility of the pressure relief valve sticking with a resulting loss of oil pressure.

The kit consists of the following:

A - One (1) pressure relief valve assembly with pump cover.
B- Six (6) pump cover attaching screws.
C - One (1) pump cover gasket
D - One (1) reinforced spring.

Condition:
This kit is to be used whoever a loss of oil pressure or suspected loss of oil
pressure is experienced. It is also to be used when any major engine repairs
are made.

Procedure:
On 1968 and 1969 Opels with A.I.R. system, it is necessary to remove the AIR
pump for access to the bypass valve plug. It is not necessary to remove the timing
chain cover assembly.

1. Remove the bypass valve plug, spring, and bypass valve check ball.
Clean the bore with a suitable solvent. See Figure I, Item E.

2. Reinstall by pall valve check ball.

3. Install new heavier spring from kit (Figure II, Item D) and discard old spring
and reinstall bypass valve plug.

4. Remove existing oil pump cover. CAUTION: The oil pump gears are not
retained in the housing; care must be taken to remove the gears when the cover
is removed so that they will not be dropped and damaged.

5. Install the new oil pump cover with relief valve, new gasket, and screws
included in kit. See Figure II, Items A, B and C.

Note: The oil pump cover must be installed with relief valve plug to the rear of
engine as shown in Figure II. It is possible to install the cover with valve plug
to the front of the engine, which will result in uncontrolled oil pressure.

Opel Service Department
Buick Motor Division
Flint, Michigan
Is there a replacement spring available for the oil punp cover fix?
 

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Opeler
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Opel GT Source May 2014 special, Part 6158-S (Replacement oil relief metal piston, new spring and 2 adjustment washers) at $25.00.
Replacement oil relief piston Part 6158 is plastic.
Oil pump gasket is Part 6011.
 

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Opeler
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2,995 Posts
Opel GT Source May 2014 special, Part 6158-S
(Replacement oil relief metal piston, new spring and 2 adjustment washers) at $25.00.
Replacement oil relief piston Part 6158 is plastic.
Oil pump gasket is Part 6011.
What would be the advantage of the oil relief metal piston vs the plastic piston?
(Longer life and/ or better sealing?)
 

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What would be the advantage of the oil relief metal piston vs the plastic piston?
(Longer life and/ or better sealing?)
I've seen the plastic pistons with uneven wear as well as the seat that it was supposed to seal. So I would 'assume' the metal piston would be a better seal for a longer period of time on a good oil pump cover.

Harold
 

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106 Posts
Hi,

I have a new engine (rebuilt 1.9 converted to 2.0L). I have been running high oil pressure but have had no other ill symptoms. I had a new mechanical oil pressure gauge and I thought that was the issue, but I swapped it with another new gauge and it is still reading high.

In reading all over the forums I came across this information, which is very helpful. I read the other articles relating to this also - at least the ones I could find.

I have 70 GT with the relief valve on the side of the timing cover, and I removed it and the ball appeared to be okay. I ordered the upgraded part from OGTS which relocates it and it came in today so I would like to install it in case that is causing my high oil pressure.

I just wasn't sure how to handle the shimming of the original valve or how to render it inoperable. Should I just remove the spring and ball? If anyone has done this upgrade I could use the help, or any other thoughts you might have.

Thanks,

Josh
 

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Opel Rallier since 1977
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1,593 Posts
You would put a heavier srping behind the ball in the side of the timing cover, or some shims behind the original spring there. By no means do you take the spring and ball out!

How high is your 'high' oil pressure?
 

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106 Posts
I should add that I am running 20/50 oil at Gill's recommendation and the engine only has a few miles on it... so I am not sure if hihg oil pressure is normal or not.
 

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You would put a heavier srping behind the ball in the side of the timing cover, or some shims behind the original spring there. By no means do you take the spring and ball out!

How high is your 'high' oil pressure?
@ Manta. Unless I have something wrong w/ the way I installed the aftermarket mechanical oil pressure gauge then it is ~100 psi. I had thought at first that this was a false reading since nothing bad had happened... like blowing up the oil filter... but I am not sure what I would have done wrong in the install. I watched some youtube videos, tried a second gauge, etc... if I installed it wrong then I am not sure what I did.
 

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@ Manta. Unless I have something wrong w/ the way I installed the aftermarket mechanical oil pressure gauge then it is ~100 psi. I had thought at first that this was a false reading since nothing bad had happened... like blowing up the oil filter... but I am not sure what I would have done wrong in the install. I watched some youtube videos, tried a second gauge, etc... if I installed it wrong then I am not sure what I did.
Did you by any chance reverse the oil pump cover when installing it? The check valve should face rearward....towards the oil pan. If it is facing forward it will cause high oil pressure.
 

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Opel Rallier since 1977
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1,593 Posts
@ Manta. Unless I have something wrong w/ the way I installed the aftermarket mechanical oil pressure gauge then it is ~100 psi. I had thought at first that this was a false reading since nothing bad had happened... like blowing up the oil filter... but I am not sure what I would have done wrong in the install. I watched some youtube videos, tried a second gauge, etc... if I installed it wrong then I am not sure what I did.
Yeah, that is high.... quite high. While I would not run 20W50 myself, that is not going to cause the 100 psi pressure. The pressure relief valve in the timing cover is not opening and working and relieving the the pressure properly, so the new cover should get things back under control. See Bob's note above!!

BTW, good you are doing this.... 100+psi at at high RPM's in these engines for 1or 2 minutes will result in excess oil pumped into the head and will leave the pan dry and starve the crank and rod bearings. BTDT almost 40 years ago.... the next race came up so fast that I did not get the pressure gauge hooked up; the relief valve had old shims, the pump had new gears, and the pressure was above 100 psi but I did not know it. First long rally stage ran uphill in a 2 mile long hollow in the Zaleski State Forest in OH, and the crank went dry....that was a short rally! I've also blown out a filter base gasket at 100+ psi in another engine.....

I don't focus on pressure any more except as a way to judge flow. Hence the aversion to 20W50....
 

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Hi. Thank you for the help. The oil pump cover is not reversed so that is not it..

After reading your story I am glad that the engine didn't burn up a bearing or something too. Thankfully I haven't really done anything since I got it built since I keep chasing down lingering issues. haha.

You would put a heavier srping behind the ball in the side of the timing cover, or some shims behind the original spring there. By no means do you take the spring and ball out!
I am going to try to do this work tonight if I can so that I can put some miles on the car this weekend.. For shimming the original spring - are there special shims I should go buy or are people using a washer behind the spring or something? I am just curious how far to shim it out and what folks are using so I don't mess it up.

Thanks again,

Josh
 

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Opel Rallier since 1977
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You can just put a few thin washers behind the spring to increase the spring pressure. It does not take a lot.

I just want to be clear.... have you just now put the new pump cover on, and have not yet run the car?
 

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okay thanks. I still have the new oil cover in the box and I have not put it on yet. I was going to do it tonight if I get the kids down early enough... or tomorrow at the latest
 

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Is the idea with the shims to keep the ball seated firmly once I install the new relief valve? This is my plan tomorrow:

427121
 

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Opel Rallier since 1977
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That is correct.. you just don't want the old relief valve acting anymore. Seems like Opel just put a stiffer spring in there for the subsequent years of production. So you are mimicking that. Knorm's service bulletin that he posted in post #9 mentions a new spring there.
 
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