Page 1 of 2 12 LastLast
Results 1 to 20 of 34

Thread: An oil pressure odysseus

Discussions of MG Sports Cars

  1. #1
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    An oil pressure odysseus

    This is going to be bit long so be warned.

    I had the engine rebuilt about 35K ago. Supposed to have been done perfectly. Everything save for the pistons was renewed, balanced, line bored, etc. VP-11 cam new billet. Rods and mains sized (supposedly). Head by Huffaker and touched up with larger valves eventually by Sean Brown. Supposed to have lasted over 100K.

    Its a 1971 daily driver with over 500K on the odometer. I just restored it again around the time of the engine.

    With the electric gauge I showed a steady OP of 70-75 lbs even in traffic and the heat of L.A.

    Moved to Oregon which is much more MG friendly weather. A couple thousand miles ago I suddenly saw the oil pressure drop 25 lbs + Obviously, I was immediately concerned.

    Went through everything I could prior to pulling the pan including buying a cheap sun pro mechanical gauge. That gauge showed the electrical gauge was WAY off. Changed the oil/filter but that wasn't it and only 4000 instead of 3500 interval. Even put in a larger oil filter.

    Bought new tri-metal bearings and a new oil pump. Pulled the pan and the caps on the rods and 3 mains I could get to. Plasti-gauged a couple rod journals. One was .0018 and the other was a depressing .003 Top of one rod journal had a slight score. The fingernail test showed the other were fine but #3 main had micro grooved and a slight burr which I carefully sanded down with 600 solvent soaked sandpaper as per crank grinding sites. None of the rods had any crush to the bears which sucked. Also found a dingle berry from a hone in the oil pan. Otherwise no metal or metallic substances.

    The uprated oil pump was fine but the part that goes into its housing was heavily scored. The rest was perfect. Put in another one just in case.

    The rod bearings looked like the came from a 100K+ engine and the backs clearly showed they had been moving within the caps. Naturally the tops were worse than the bottoms.

    Followed the manic no dust policy using dust free wipes and carefully cleaned and dried the journals and caps/rod tops. Proper use of assembly lube.

    Crank was polished and not turned. I had at one point put in a new crank and helping mechanic though it was better to polish than turn. STD beading but I think it should have been turned. Oh well.

    Reassembled and let the car get oil pressure prior to firing. No change in oil pressure. Yesterday was a hot day here and was stuck in freeway traffic. The SunPro read at the worst 48 speed and 25 idle. Once it cooled down on the road it went up to 54/35.

    Got a used mechanical Smiths oil pressure gauge (thanks Rut!) and the associated line/junction. Its having some teething but when checked was in perfect calibration. Just dealing with a sticky needle right now.

    I'm at a complete loss why the oil pressure didn't get any better. Spoke to one person who insisted it was the cam bearing but the cam looked fine and I'm pretty sure I had them line bore it but with what I saw I think the Speed Shop in Burbank CA just charged me and didn't do much of anything they were paid to do or did it very badly. Head came off twice and I finally gave up and sent it to Sean Brown who said guides were in backwards and wrong like intake in the exhaust etc. Once fixed the car ran and still runs great.

    The only reason why I didn't put in new pistons was because one previous mechanic's shop made a mistake and instead of skimming the block they decked it. Compression is high and I didn't want it any higher.

    Hot compression is 190/187/204/192

    I did the math on the compression table on the net but it shows about 9.1:1 which can't be with the compression.
    The head is 42.6cc. The piston dish is 6.5cc. The pistons are .015 below the deck.

    No rod knocking. Car runs great but oil pressure is freaking me out. Being a daily driver I can't put it down for a month or more waiting on a machine shop. Plus I think the block is toast with almost zero deck. Oh, and no budget since I put so much into the car to make it new.

    So, um, help?

  2. #2
    Jedi Knight Brinkerhoff's Avatar
    Join Date
    Dec 2010
    Location
    Traverse City MI. USA
    Posts
    1,168
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    6
    Thanked in
    3 Posts

    Re: An oil pressure odysseus

    A lot of oil pressure can be lost through the rocker shaft and bushings , though a fresh lower end can mask this area until the engine loosens up a bit.

  3. #3
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    Rocket shaft was new and hardened. The bushing was specially reamed to shaft and appear fine. But I can check again. Rockers were faced. Thought I was doing everything properly.

  4. #4
    Jedi Knight Brinkerhoff's Avatar
    Join Date
    Dec 2010
    Location
    Traverse City MI. USA
    Posts
    1,168
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    6
    Thanked in
    3 Posts

    Re: An oil pressure odysseus

    What did the main journals plastiguage to ?

  5. #5
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    I confess I got depressed at the rods so I stopped measuring. Here are shots of all the bearings. T= top B=bottom. Also is the end of the oil pressure shaft that was replaced.
    Attached Images Attached Images

  6. #6
    Jedi Knight Brinkerhoff's Avatar
    Join Date
    Dec 2010
    Location
    Traverse City MI. USA
    Posts
    1,168
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    6
    Thanked in
    3 Posts

    Re: An oil pressure odysseus

    The bearings are from the crankshaft that was polished and not turned?

  7. #7
    Jedi Knight Brinkerhoff's Avatar
    Join Date
    Dec 2010
    Location
    Traverse City MI. USA
    Posts
    1,168
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    6
    Thanked in
    3 Posts

    Re: An oil pressure odysseus

    It looks like either the crank journals are not round or the engine was dry started. You don't have any evidence that the pistons were hitting the cylinder head or gasket? Did you plastigage with the old bearings or new?

  8. #8
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    The engine was not dry started. I started the engine and everything should have had assembly lube. No evidence the pistons hit the cylinder head. That was a concern. I did not plasti-gauge the old bearings. Those were readings from the new bearing.

  9. #9
    Jedi Knight Brinkerhoff's Avatar
    Join Date
    Dec 2010
    Location
    Traverse City MI. USA
    Posts
    1,168
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    6
    Thanked in
    3 Posts

    Re: An oil pressure odysseus

    Probably should've turned the crankshaft. I hate to be the first to say it but you've probably got metal throughout the oil galleys in the engine now. Either live with the oil pressure or redo the engine.

  10. #10
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    Well as mentioned 'probably' however too late and i think the speed shop did not do what they promised and charged for.. Right now no way to redo it either time or budget. I've been screwing with the new/used oil pressure gauge and hopefully I have it working smoothly. But the numbers aren't good. Pretty much the same as the cheapo SunPro.

    One odd thing was somehow I forgot to tighten the oil filler cap and the oil pressure never went below 50 lbs. I was so excited until I realized there was no reason for the idle to have raised. When I checked the cap and tightened it. OP went back to its depressing state.

    I guess I need to know how many realistic miles I have got left. The car runs great, really great. But the low oil pressure is going to do it damage...

  11. #11
    Jedi Knight Brinkerhoff's Avatar
    Join Date
    Dec 2010
    Location
    Traverse City MI. USA
    Posts
    1,168
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    6
    Thanked in
    3 Posts

    Re: An oil pressure odysseus

    Run it for 500 miles and take an oil sample , send it out for analysis. It should tell you if wear is accelerated. It might not be as bad as we think. IMG_0246.jpg
    Attached Images Attached Images

  12. #12
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    Wow. Gorgeous engine! Whom do I send the sample. What are they going to tell me? How much metallic particles are in it?

  13. #13
    Jedi Knight Brinkerhoff's Avatar
    Join Date
    Dec 2010
    Location
    Traverse City MI. USA
    Posts
    1,168
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    6
    Thanked in
    3 Posts

    Re: An oil pressure odysseus

    Call around to the nearest place that works on Diesel trucks, you can usually buy a kit that comes with a small tube that you collect some oil while its draining , write down the mileage and type of oil and send it off. Yes, they'll give a complete breakdown of what particles are in the oil and an analysis of what the particles are from and whether you are in the normal range or not.

  14. #14
    Yoda PAUL161's Avatar
    Join Date
    Jan 2005
    Location
    Locust Grove, Oklahoma
    Posts
    9,357
    Thanks Thanks Given 
    1
    Thanks Thanks Received 
    40
    Thanked in
    37 Posts

    Re: An oil pressure odysseus

    Our 72 has 75 lbs at startup idling and drops to 65 when hot. Mechanical gage which has been tested for accuracy. Never an over pressure issue since engine was rebuilt in 2000, pickled and stored until 2005 when placed in car. PJ

    Remember, Never Forget
    We Live In The Land of The Free
    Because of The Brave

    How good it feels, the hand of an old friend! Longfellow

  15. #15
    Great Pumpkin DrEntropy's Avatar
    Join Date
    Sep 2005
    Location
    Elsinore, DK
    Posts
    32,943
    Thanks Thanks Given 
    23
    Thanks Thanks Received 
    62
    Thanked in
    61 Posts

    Re: An oil pressure odysseus

    Has the pressure relief valve & spring been replaced at rebuild?
    '64 MGB, '67 Lotus Elan S-3 DHC,'69 Lotus Elan +2
    '78 Alfa Romeo Spider-undergoing surgery: O=\*/=O
    '84 300D Turbo-"Diesela"-Now my Daily: Oo|≣|oO
    '02 Toyota Camry- SWMBO's 'new-to-her' Daily. <sigh>
    Chaos & Mayhem PTY, LTD..C.I.O. & Floor Sweepervisor

  16. #16
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    Well, I'm jealous of everyone's normal OP.

    Yes the pressure relief spring was replaced at the rebuild but not sure if the valve itself was replaced. As I understand it, that is only for top OP. I can see it blow off when the car starts up but when hot it drops to where the bottom of the gauge needle just clears 50 by about a 1/16th of an inch. At idle it will go down between 25-50 and left alone and not blip the throttle it will creep towards 25. I cannot imagine what else could be causing this other than the big end mains which I couldn't do with the engine in the car.

  17. #17
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    Using a football term, did a hail mary and had the pressure relief valve/spring/packing replaced. The packing gave me some more pressure when cold and not real hot in traffic. Even the shop I used was mystified why the pressure had dropped. Said the engine sounded great. The only thing they recalled was one time a galley plug got a little loose and was leaking pressure. They also said the valve train was great so definitely getting oil….

  18. #18
    Yoda PAUL161's Avatar
    Join Date
    Jan 2005
    Location
    Locust Grove, Oklahoma
    Posts
    9,357
    Thanks Thanks Given 
    1
    Thanks Thanks Received 
    40
    Thanked in
    37 Posts

    Re: An oil pressure odysseus

    I'm not a Healey guy, but engines are engines and with 25 lbs at idle and 48 lbs at speed, I wouldn't worry about it not getting enough oil. I would keep a close eye on the pressure however, to be sure it remains the same and doesn't slowly drop over time. If it does, you have no option but to redo it! Hate to say it, but I would never put a crank in an engine I'm rebuilding that hasn't been x-rayed and all journals trued up. The oil galleys should have been cleaned before rebuilding also. I think your rebuilder didn't do the job properly. JMHO. PJ

    Oops! Don't know why I thought we were speaking of a Healey engine. Makes no difference though, their all the same, just more cylinders!

    Remember, Never Forget
    We Live In The Land of The Free
    Because of The Brave

    How good it feels, the hand of an old friend! Longfellow

  19. #19
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    The only thing I can imagine is that dingle from the hone was laying in hot recirculating oil for 35K miles and slowly melted putting destructive abrasion into the oil. I changed oil/filter every 3000 miles and after initial 500 miles but maybe that?

    Yes, all the things you mentioned were to have been done by the builder which its clear either were not done or done poorly.

    The only option is if the OP drops more I need to put in a new short block. The same shop that only works on Brit cars has a rebuildable short block and we discussed pricing. Will hope the car runs while I save up for the a rebuilt SB and have them slug it in.

  20. #20
    Member max71's Avatar
    Join Date
    Apr 2006
    Location
    Oregon
    Posts
    49
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: An oil pressure odysseus

    Paul - just to be clear. Your hot pressure is 65 lbs whether at speed to hot idling in traffic?

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •