Reduced Oil Pressure, Was Ok!

[dcc 855]

I have one at home somewhere, ill dig it out. a mechanical oil pressure gauge will give you the best and most accurate understanding of what your engine is doing. without the bolt tightened up you're pissing into the wind. you need to understand that the oil pump has a mechanical drive off of the crank. the drive is powered by the FRICTION provided by the correctly tensioned lower pulley bolt. before you go buying any gauges, invest in a torque wrench and tighten the bloody thing!

[mhyphenl 10 1 Cars]

I have one at home somewhere, ill dig it out. a mechanical oil pressure gauge will give you the best and most accurate understanding of what your engine is doing. without the bolt tightened up you're pissing into the wind. you need to understand that the oil pump has a mechanical drive off of the crank. the drive is powered by the FRICTION provided by the correctly tensioned lower pulley bolt. before you go buying any gauges, invest in a torque wrench and tighten the bloody thing!

Agreed, and I've got a great torque wrench. This morning, engine in gear, handbrake on the ceiling I wrenched it and the crank pulley was turning. It may have been the gears catching up to take up the slack but being in a rush to get to work I stopped worried I may be damaging something. I'll jam the flywheel tonight and torque it up to spec tonight. If there's nothing else easy to check I'll leave it at that until tonight!

[welshpug 1,622]

If you do it in gear rather than locking the flywheel you will turn the crank a little due to the sprung centre in the clutch friction plate, not an issue as it will soon stop turning as you compress them fully and the bolt will keep turning if the threads are clean.

[mhyphenl 10 1 Cars]

Hi All,

 

Ok, just snook out from work and tightened the bolt, 109nm according to the book. Managed to click so ok. Still no improvement so I need plan B. I'll try and get the actual pressure tested, what figures should i be getting hot / cold, tickover / revs?

[ORB 227 1 Cars]

Who re-built the engine?

[sport1901966 8]

Got the information below, its for the Mi16, but I believe it should similar for the 8v

 

Edited April 11, 2013 by sport1901966

[mhyphenl 10 1 Cars]

Who re-built the engine?

Me I'm afraid so there could be a million things wrong! I was very particular in working out the correct shells etc and the plastiguage said yes! Didn't replace the oil pump though as it seemed fine!

Thanks for the figures by the way!

Edited April 11, 2013 by mhyphenl

[Slo 283 1 Cars]

Correct torque on the pulley bolt isn't only important for the oil pump, it also hold the cambelt drive pinion/cog/thing in place, you can imagine what damage will result if the pulley falls off as there will be nothing to hold it in line with the camshaft. When you say the red light is coming on do you mean the tiny light on the oil guage or do you mean the stop light? or both?

[mhyphenl 10 1 Cars]

Actually it's the all the red lights and the stop light, temp and oil! Could this just be the revs dropping low enough to switch all the warning lights briefly. It only happens when the revs drop too low! It doesn't change the fact that the pressure gauge is reading very low and was reading higher!

[Slo 283 1 Cars]

I wouldn't trust the guage or rather the sender unit for it as far as you can throw it, its urgent you get the pressure properly checked now as already mentioned the shells wont last long if they aren't getting the proper supply of oil not to mention the camshaft bearings if you are driving it daily in this state without knowing for sure its only a matter of time before it will be beyond economical repair if repairable at all

 

ps dont see how temp light is relevent? Is it wired up properly?

Edited April 11, 2013 by Slo

[mhyphenl 10 1 Cars]

What I mean is, if you stall the car the warning lights come on, I think the lights are flickering because the revs are dropping low enough to nearly stall therefore the lights flicker! The fact the pressure gauge is very low may just be coincidence.

As for the actual pressure, quite right, need to know the facts before damage is done! I really hope there hasn't been, I spent ages getting bearings right! I'm going to pop down the road and get it checked.

[mhyphenl 10 1 Cars]

Right, none of the local garages seem to have an oil pressure tester so not wanting to drive far if at all I'm going to buy one. One guy I spoke to seemed to thing that it's unlikely the guage sender has changed in operation despite their inaccuracy, in his experience they either work as they work or not at all. ie what it shows for 3 bar is unlikely to change. He asked me if it was rattleing and under reasonable load it does a bit so he thinks there is something wrong on the bottom end. I was painstaking about the torqueing and tolerances and making shure the bearings went in the right way etc, what I didn't check were the channels in the block to make sure they were clear! Have I done a bad murder!?!

[pug_ham 240 3 Cars]

can you get a toothed tool to do it properly? Where on the gearbox case do you lock it?

Yes;

 

I have a snap on one & a Franklin one, £15 or less from the usual auction site.

 

g

[mhyphenl 10 1 Cars]

Ok, another rookie question. Is the low pressure switch a suitable place to test the oil pressure? It's the only place I can half get to, I need to remove the power steering pipe to even get to that, alternator may have to go too! There isn't another place is there?

[2052NV 24]

Dont drive it any more!!!! haha get the proper guadge on and confirm it, then take rocker cover off and check all the o-rings on your camshaft spray bar are there/ not split and the bar is seated properly, then check for cracks in the bar its self. if that is ok your going to have to bite the bullet and remove the sump (which can happily be done in place and really isnt a big thing). Check the oil pump bolts are tight. Check you fitted the spacer plate (L bracket thing) under the oil pump. also check the plug (square drive) next to the pressure feed from the oil pump is tight (i always put thead lock on that plug). Then check all your piston oil spray bars are tight. Then start worrying about bearing clearances etc.

[2052NV 24]

also pressure sender is the easyist place to hook up the guage.

[pug_ham 240 3 Cars]

Ok, another rookie question. Is the low pressure switch a suitable place to test the oil pressure? It's the only place I can half get to, I need to remove the power steering pipe to even get to that, alternator may have to go too! There isn't another place is there?

 

The oil pressure switch or oil pressure sender are the only two points you can fit the oil pressure gauge, either is suitable as they are on the same gallery supply.

 

g

[mhyphenl 10 1 Cars]

Thanks Robert,

 

That's just what I was after, a few avenues to check before I panic! I've had to work over the weekend so still not checked the actual pressure but will tonight. I've got PAS and air con so even the pressure sender and switch are a bugger to get to, I think I can get there with the alternator off though! Thanks pug_ham, thought that was the case but wanted to check as never had to deal with this! I'll check the top of the engine first as I need to check the valve clearances anyway as one or two sound a bit noisy anyway!

 

A word on warning lights, if the oil pressure was low would the pressure light and the stop light come on, just like if the water was over temp? The reason I ask is because when the revs were dipping all three ( Oil pressure, stop and water temp) light came on suggesting the engine was about to stall and not in fact the switches kicking in. If the pressure on tickover was low enough to engage the oil pressure switch then only the oil pressure light and the stop light would illuminate!?

 

Thanks everyone so far on this BTW

 

Martin

[mhyphenl 10 1 Cars]

Update,

 

Took off the rocker cover and prepared myself for priseing the oil spray rail to find it lifted off with no effort! O rings had gone hard and squared off, don't know why I didn't spot that on rebuild, probably rushing knowing me. Anyway, replaced o rings and it has made a small difference, (a couple of mm on the guage of no accuracy!)

I'm now doubting weather there was an o ring on the hole from the pump into the block, (if there should be one?!)

I still haven't checked the actual pressure as I've got to take so much stuff off just to get to the pressure sender, it was easier to just check and change the oil rail o rings!

 

If someone can confirm the need for an o ring on the pump that would be good!

 

All the best,

 

Martin

[sport1901966 8]

There's no o-ring between the pump and the block, just the L-shaped bracket. If you are really concerned about the joint you can use some non-curing metal-metal seal like stag wellseal just to be sure.

[mhyphenl 10 1 Cars]

If its not meant to be there then I guess the system should be able to cope as is!

[mhyphenl 10 1 Cars]

Ok then, after a hectic weekend I finally got the Sump off and checked over the oil Pump, there seemed to ba alot of silt in the sump which was a worry and when I opened the pump up I found bad things

 

 

 

Bad scoring on the pressure relief piston which was stuck fast probably slightly open which was causing most of the issue with pressure, also bad scoring on the mating face where the pump cogs turn. This seems to be a lesson in not getting your block aquablasted and or being extra anal about making sure every last bit of blast media is expelled. Next on the the bearings, I'm pretty sure I know what I'll find.....

[Tom Fenton 1,525]

Oh dear, but at least you have done something about it before it started knocking, so the crank and rods should be re useable with a check and grind of the crank if needed.

[mhyphenl 10 1 Cars]

.... and yes, scored face on the first bearing I look at.

 

 

The car has done 300 miles, it looks like it's done 30000! I know that I need to re do the bearings, the faces on the crank look fine but I will re measure. I have a fresh oil pump.

 

What I need to know is what the best course of action is in terms of making sure there's none of the cr*p left in the engine. I thought the best bet would be to put the worn stuff back, clean the sump the run some more fresh oil through a new filter, maybe do that a couple of times with cheap oil to flush it through before removing the engine and starting a fresh. Or am I never likely to find all the particles?! How on earth do you clean the inner deapths of an engine, I haven't looked at the damage to the head yet.

[Tom Fenton 1,525]

Needs to come out, be totally stripped, pull all oil gallery plugs, and then pressure wash it to death through all the oil ways, then go through with gallery brushes, then pressure wash again. Same for the crank drillings.

 

If you don't do this you are always at risk of a lump of debris getting into the oil flow and scrapping all your bearings once more.