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Oil Pressure Nightmares


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I'm in the process of having my engine stripped and rebuilt to, hopefully, correct an oil pressure problem that has been ongoing for some time. It is a 1987 GTE 2.0 injected coupe. The mechanic has checked my oil pressure and it ticks over at approx. 20lb with some fluctuations between 18lb and 28lb. On occasions it can drop as low as 10lb and with revs at 1500 - 2000 it can go off the scale ie. well over 100lb. The engine has been worked on before (3 years ago) and is an amalgamation of two engines using the 'best' parts from each. The pictures below were taken this morning and I can only assume the parts are all correct for my car (are carburettor/injected engine blocks, heads different?). The photo of the head with a curled up piece of metal in the oil return must surely be an oversight/error by the previous mechanic - but does it serve a purpose ? why would you do it ? The oil pump housing was changed 18months ago, part no. 90090599, which I am told is correct although I can't find it on the parts disc. The mechanic is continuing to strip parts down and check for any defects, dirt, swarf etc. that might lead to an answer but any help/suggestions would be much appreciated. Could the high pressure and low pressure be two separate issues and not one ?  Cheers, Steve.

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to be honest i dont think you have a low oil pressure issue. dropping to as low as 1/2 bar ish on the guage at idle especially when hot shouldnt be an issue.especially if your using a thinner oil than

Hi Steve Here are some pics of the cam wheel and timing chain. How does £60 for the cam wheel and £20 for the timing chain sound? I have a few spare gaskets and if they are any use you can h

I have quite a few pics of my engine build that might help to cross reference http://www.theopelproject.com/ you might need to look through a few posts but i have lots of pics of the front timing

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Pretty sure that the curled up piece of metal that you show in the photos is the oil level raiser,  it should protrude upwards towards the cam (if that makes sense ) , it keeps extra oil in the head by simply raising the level of the oil return path. It may have dropped down into your head . 

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Yes, the metal sleeve a later standard fitment. But you need one of these inserts to replace it...fits inside the head from the top...

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Oil pump parts are expensive to replace, put up some photos of your oil pump parts, we may be able to give you an appraisal...

Do you still have the old head gasket, I notice it has additional cooling holes, if you do, does it show who it is made by?

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I presume the oil raiser (coiled up piece of metal) slid down when you took the head off? Its usually fixed in the head pretty tight and as pointed out about, it should stick out of the top of the head.

Where is the oil pressure gauge located on your engine? front timing cover i presume? Have you checked the oil pressure relief spring and plunger in the timing cover?

Page 53 on this link

http://www.theopelproject.com/l/wp-content/uploads/2020/04/A-Series-Opel-Manta-Engine-Setion.pdf

 

Andy

 

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Thanks for the replies above, at least I now know the oil level raiser is meant to be there.

Pete - I will order one of the inserts you show as I've seen them advertised on eBay etc. I will try and get some pictures of the oil pump parts when I go back to mechanics on Monday. He did say that he thought my pump gears were slightly worn (where do you get new ones?), which may account for the low pressure, but the high pressure ?? I will also try and get a picture of the existing head gasket and any identifying marks. I have bought a complete engine gasket set by Ajusa for this rebuild.

Pete/Andy - The oil pump pressure plate (no gasket used) was bought new from edelschmiede approx. 2 years ago and should be ok but I appreciate that a pressure reading over a hundred may suggest otherwise. The oil pressure switch is located on the front timing cover and has been there since the engine was last worked on 3 years ago. The existing oil level raiser can be moved by hand up or down, without much effort, and so wasn't necessarily tight enough to remain in place but should the gasket below prevent it dropping or should it be tight enough to stop it moving, even when hot and under pressure?

Steve.

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Update - the mechanic thinks he may have discovered what is causing my low oil pressure - the oil pick up pipe did NOT have a gasket fitted, and having read the link supplied by 611 Andy (thank you), we have subsequently cleaned the release valve and all is ok with that but noticed that the plate had been put on the wrong way round. As the link states the valve should aim to the back of the car whereas mine was pointing forward - presumably preventing it from working correctly - yet to be reassembled to confirm. The replacement oil level raiser has also been ordered and will be fitted in due course.

Old gasket - but no makers name visible.

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to be honest i dont think you have a low oil pressure issue. dropping to as low as 1/2 bar ish on the guage at idle especially when hot shouldnt be an issue.especially if your using a thinner oil than 20w. providing the pressure builds up relatively good on increased rpm.     however !

the high pressure is more of a concern .with a cold engine it is possible to see 4 or 5 60-80 psi)bar at higher revs but i wouldnt want it go  up to 100 psi incase you blow out a gasket or plug somewhere in the pressure side.

the things to check here especially if your engine has had a few parts swapped is that your running early spec ,mid or late systems.

early oil pumps used a gasket ( the type with a flat coverplate )as did the mid type with the pressure releif valve built into the cover.but very late ones didnt have a paper gasket just a liquid sealant.if you put a gasket on by mistake the idle pressure goes too low.  vice versa can cause seized gears because of too little/ no end clearance.

the pressure releif valve on early cars is on the side of the engine by the timing chain tensioner whereas the others have it built into the oil pump cover as mentioned. if you put a flat cover on by mistake you will have no releif at all and the pressure will increase with rpm.

so you need to be sure which type of timing case / oil pump you have got and that the parts are all correct.

 

one thing i noticed in your pictures although it may just be a trick of the light / camera angle is the inlet valves in your head look to be way too far in / recessed. ? ? 

 

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The oil pump cover with the pressure bypass valve fitted the wrong orientation would mean it would not open, so there is your reason for the extremely high pressure.

I agree with Cam in Heads opinion on the low pressure side, unless it's been measured properly at the engine the gauge could easily be 5psi out, especially if the switch has been subjected to prolonged over pressure.

 

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25 minutes ago, cam.in.head said:

to be honest i dont think you have a low oil pressure issue. dropping to as low as 1/2 bar ish on the guage at idle especially when hot shouldnt be an issue.especially if your using a thinner oil than 20w. providing the pressure builds up relatively good on increased rpm.     however !

the high pressure is more of a concern .with a cold engine it is possible to see 4 or 5 60-80 psi)bar at higher revs but i wouldnt want it go  up to 100 psi incase you blow out a gasket or plug somewhere in the pressure side.

the things to check here especially if your engine has had a few parts swapped is that your running early spec ,mid or late systems.

early oil pumps used a gasket ( the type with a flat coverplate )as did the mid type with the pressure releif valve built into the cover.but very late ones didnt have a paper gasket just a liquid sealant.if you put a gasket on by mistake the idle pressure goes too low.  vice versa can cause seized gears because of too little/ no end clearance.

the pressure releif valve on early cars is on the side of the engine by the timing chain tensioner whereas the others have it built into the oil pump cover as mentioned. if you put a flat cover on by mistake you will have no releif at all and the pressure will increase with rpm.

so you need to be sure which type of timing case / oil pump you have got and that the parts are all correct.

 

one thing i noticed in your pictures although it may just be a trick of the light / camera angle is the inlet valves in your head look to be way too far in / recessed. ? ? 

 

Thanks for the above info - I'm happy that I have the correct oil pump housing (90090599) and plate with relief valve (replaced with matching part number) and know not to use a gasket on my car. However, your last comment - means nothing to me - but I'll ask the mechanic to check it out and see if anything is wrong, thank you for pointing it out.

6 minutes ago, Jessopia74 said:

The oil pump cover with the pressure bypass valve fitted the wrong orientation would mean it would not open, so there is your reason for the extremely high pressure.

I agree with Cam in Heads opinion on the low pressure side, unless it's been measured properly at the engine the gauge could easily be 5psi out, especially if the switch has been subjected to prolonged over pressure.

 

Thanks for confirming the plate orientation. Whilst annoying it's a nice easy, cheap fix (for a change). My car had the replacement oil pump housing fitted at my local garage and retained the issue with the oil light coming on & didn't 'feel right' when driving and so it has only done about 40 - 50 miles since - would you, therefore, recommend changing the pressure switch incase of any damage?

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sorry i cannot view all your /  the pictures of your housing as only a forum member but jess sorted you out there anyway.

your mechanic may not see anything wrong with your valves unless he has something to compare with so you may need some close-up pictures from other members or you could measure the stem protrusion on the other side maybee. if they are too deep it will be the same effect as lowering the compression ratio .

one thing i would check re the high pressure in case its done any damage . the head has an oil gallery that runs across the top to feed the cam followers and the studs . there should be a pressed in cap along this . just make sure its not blown out with the pressure !  it will be obvious if it gone because you will see the small hole !

this would obviously lower the oil pressure especially at idle 

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1 hour ago, les87GTE said:

Thanks for confirming the plate orientation. Whilst annoying it's a nice easy, cheap fix (for a change). My car had the replacement oil pump housing fitted at my local garage and retained the issue with the oil light coming on & didn't 'feel right' when driving and so it has only done about 40 - 50 miles since - would you, therefore, recommend changing the pressure switch incase of any damage?

Not at this stage, just do not believe the reading to be accurate. All you are looking for is a stable reading at low rpm and the fact it will rise to reasonable reading at rpm without trying to snap the needle to show it's too high. However, the oil light coming on is another issue. That would trouble me more. The high pressure may have caused damage to seal in the chain tensioner that would allow a lot if oil pressure to be lost, was there any rattle when you had the low pressure? It could effectively retard the cam timing if it's too slack, that may be the  poor running that you think you noticed.

I think you should definitely be dropping the sump, checking big end and main bearing wear at the back of engine (furthest from pump) and also the chain tensioner too.

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i assumed his engine is currently in bits ? 

if so maybee the combination of oil cover wrong way,suction pipe gasket missing may be the issue here. looks like its having a thorough inspection for any other faults 

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I have quite a few pics of my engine build that might help to cross reference http://www.theopelproject.com/

you might need to look through a few posts but i have lots of pics of the front timing etc.. might help and there. Also more sections from the manual.

This one shows the oil ways, page 11

http://www.theopelproject.com/wp-content/uploads/2018/12/Opel-Manta-Engine-Spec-and-Cyliner-Head-Rebuild2.pdf

and front cover

http://www.theopelproject.com/wp-content/uploads/2018/12/Opel-Manta-front-cover-oil-pump.pdf

worth a good check of all oil ways to make sure no blockages etc..  

 

Andy

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13 hours ago, Jessopia74 said:

Not at this stage, just do not believe the reading to be accurate. All you are looking for is a stable reading at low rpm and the fact it will rise to reasonable reading at rpm without trying to snap the needle to show it's too high. However, the oil light coming on is another issue. That would trouble me more. The high pressure may have caused damage to seal in the chain tensioner that would allow a lot if oil pressure to be lost, was there any rattle when you had the low pressure? It could effectively retard the cam timing if it's too slack, that may be the  poor running that you think you noticed.

I think you should definitely be dropping the sump, checking big end and main bearing wear at the back of engine (furthest from pump) and also the chain tensioner too.

Thanks again for the additional information, it has all been passed on to my mechanic to check out. The engine is currently in bits with everything being checked for blockage, damage, wear etc. with the view of replacing anything the isn't 100% right. Any more info or tips at this time would all be welcomed.

 

9 hours ago, 611 said:

I have quite a few pics of my engine build that might help to cross reference http://www.theopelproject.com/

you might need to look through a few posts but i have lots of pics of the front timing etc.. might help and there. Also more sections from the manual.

This one shows the oil ways, page 11

http://www.theopelproject.com/wp-content/uploads/2018/12/Opel-Manta-Engine-Spec-and-Cyliner-Head-Rebuild2.pdf

and front cover

http://www.theopelproject.com/wp-content/uploads/2018/12/Opel-Manta-front-cover-oil-pump.pdf

worth a good check of all oil ways to make sure no blockages etc..  

 

Andy

As above, thanks for everything you have mentioned - the links have been forwarded to the mechanic and I'll update later in the week when I know more

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2 hours ago, les87GTE said:

Thanks again for the additional information, it has all been passed on to my mechanic to check out. The engine is currently in bits with everything being checked for blockage, damage, wear etc. with the view of replacing anything the isn't 100% right. Any more info or tips at this time would all be welcomed.

 

As above, thanks for everything you have mentioned - the links have been forwarded to the mechanic and I'll update later in the week when I know more

Excellent, good to hear it's all getting checked, it is definitely the best way. 

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Progress being made, the reason I mentioned your head gasket, is some replacement ones don't have all the smaller round holes as your one has for block to head transfer. A tip or pre  engine start (sans spark plugs) up is to fill you oil pump with vaseline before fitting the pump cover as will aid the oil being pulled into the pump....

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On 09/11/2020 at 18:00, Jessopia74 said:

The oil pump cover with the pressure bypass valve fitted the wrong orientation would mean it would not open, so there is your reason for the extremely high pressure.

I agree with Cam in Heads opinion on the low pressure side, unless it's been measured properly at the engine the gauge could easily be 5psi out, especially if the switch has been subjected to prolonged over pressure.

 

I did this it blew my oil filter seal out. After a full rebuild and repaint I wasnt best pleased with myself 🤦‍♂️ 

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Below are a few photo's of my oil pump housing and pump gears. My mechanic is worried about the scoring and has suggested replacing the gears and possibly the housing. From what you can see, difficult I know, would anyone agree that they need to be changed ? Would you describe it as light, normal or excessive wear ?

I have seen the gears available on ebay for £300 but a new housing ? Should I need to replace can anyone recommend the best place to try ?

Thanks, Steve.

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5 hours ago, les87GTE said:

Below are a few photo's of my oil pump housing and pump gears. My mechanic is worried about the scoring and has suggested replacing the gears and possibly the housing. From what you can see, difficult I know, would anyone agree that they need to be changed ? Would you describe it as light, normal or excessive wear ?

I have seen the gears available on ebay for £300 but a new housing ? Should I need to replace can anyone recommend the best place to try ?

Thanks, Steve.

 

I agree, that needs to be replaced, probably the worst wear I have seen on a CIH pump 😬. There are good second hand units out there, sure a member on here would be able to supply you one with possibly pump gears too. Post a WANTED thread up, or message Carl - think he had a 2.0e block available that he might sell front off

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you said earlier that the complete housing has been changed recently so im assuming a used one was fitted not new because that amount of scoring if it was new suggests that theres a lot of debris floating around in that engine. that wear will also explain a low pressure at idle although yours was not that bad realy .certainly not as bad as that housing suggests.

someone will have a better one they will sell you im sure .

how did the engine actually run before you stripped it ? was it ok other than the oil pressure issues,timing chain quiet ,cam quiet etc . power ok ? 

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On 12/11/2020 at 13:27, Jessopia74 said:

I agree, that needs to be replaced, probably the worst wear I have seen on a CIH pump 😬. There are good second hand units out there, sure a member on here would be able to supply you one with possibly pump gears too. Post a WANTED thread up, or message Carl - think he had a 2.0e block available that he might sell front off

Reluctantly, I have to agree too. I will post a wanted thread and see what comes up. The current housing I bought off of Carl but It didn't look like that when it was fitted and so, as suggested by cam.in.head, there must be some debris in the oil causing the problem.

 

On 12/11/2020 at 17:16, cam.in.head said:

you said earlier that the complete housing has been changed recently so im assuming a used one was fitted not new because that amount of scoring if it was new suggests that theres a lot of debris floating around in that engine. that wear will also explain a low pressure at idle although yours was not that bad realy .certainly not as bad as that housing suggests.

someone will have a better one they will sell you im sure .

how did the engine actually run before you stripped it ? was it ok other than the oil pressure issues,timing chain quiet ,cam quiet etc . power ok ? 

The housing was replaced last year, bought off Carl, vapour cleaned and fitted by my local garage but, as stated above, it didn't look bad at all when fitted. My original gears were re-used but I will now look to replace everything - housing, gears and chain guides.

As for the engine running beforehand it all sounded ok. A little 'tappy' up top but, I felt, it lacked a little power. When I bought my first new Manta in 1985, an 1.8s Berlinetta Coupé it was capable of reaching the 120mph + that the dial suggested but my current car struggles to get to 100mph. My mechanic has found the compression is down on two pistons - 90psi instead of 140psi - and he's still looking for any more problems ( hopefully he won't find too many ).

17 hours ago, ANDY ABBOTT said:

Yep time to replace. I had same issue with my i240 but we cought this during the rebuild so just replaced the whole timing cover and gears. 

Curious - did you find new or use good second hand parts?

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Be a little careful if you replace all the chain guides as i had a problem with an aftermarket make of the tensioner being longer than the original which stopped you getting the cam wheel on. Took me ages to work out the issue.

I also have a new timing chain if you are looking for one? as bought two different ones to make sure the chain i had wasn't the wrong length and causing the issue. I also have a new cam gear if you are sticking with standard? as got a kit which it was included in and i dont need it as running adjustable on mine. Might have a few more parts like gaskets etc.. if you need them?

Just let me know what parts you need and i can have a look and see what i have.

 

Andy

Doesn't look much different but enough to stop you getting the cam wheel on!!

GM-chain-guide-1000x660.jpg

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11 minutes ago, 611 said:

Be a little careful if you replace all the chain guides as i had a problem with an aftermarket make of the tensioner being longer than the original which stopped you getting the cam wheel on. Took me ages to work out the issue.

I also have a new timing chain if you are looking for one? as bought two different ones to make sure the chain i had wasn't the wrong length and causing the issue. I also have a new cam gear if you are sticking with standard? as got a kit which it was included in and i dont need it as running adjustable on mine. Might have a few more parts like gaskets etc.. if you need them?

Just let me know what parts you need and i can have a look and see what i have.

 

Andy

Doesn't look much different but enough to stop you getting the cam wheel on!!

GM-chain-guide-1000x660.jpg

Thanks for all the above Andy. I'm going to see my mechanic on Monday morning to get his 'shopping list' of parts he would like me to acquire for the rebuild. However, I am in the process of trying to collect some original spares, for future use, as all will be staying standard with my engine. 

Steve.

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no problem, Steve.

The cam wheel is genuine, the chain made by Piper cross i think (as i think you will be lucky to genuine now) and i think you might find timing guide hard to get genuine ones as well. once you have you list post on here and we can all see what we have spare and see what genuine stuff people have lying around.

 

a few part numbers here. i think i might have a couple of the seals spare. i will have a dig through my box of spares.

http://www.theopelproject.com/?page_id=636

 

Andy

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