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Oil Pressure Oddity


Anglefire

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HI I hate to bring bad news to the table, my oil pump was new, and when i checked the tolerances they were all between 50 & 100 % out the whole thing was as slack as a yack, Mr Witor put me right with one of his upgraded units, when i checked the tolerances they are as tight as a n**s bum,

To check the PRV seat get your little mirror and a torch 

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1 hour ago, Guppy916 said:

HI I hate to bring bad news to the table, my oil pump was new, and when i checked the tolerances they were all between 50 & 100 % out the whole thing was as slack as a yack, Mr Witor put me right with one of his upgraded units, when i checked the tolerances they are as tight as a n**s bum,

To check the PRV seat get your little mirror and a torch 

Mine was a new pump and I’m sure when I checked it, it was ok.  But I see the blueprinted one from him is only a fiver more than the standard one. (Not that I think he does one for the spitfire.)

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I bought a new USB camera which came today - certainly better than my old one - but still not brilliant - one issue being which way up is the camera as its round ;) 

It does video as well as still - tried both and the best shot I got is this one (The video needs more practice!) 

Snap_004.jpg.d465c499df65cb66fafbfc9c917713f8.jpg

Whilst it doesn't look bad, I'm not sure the seat is very clean? Or more importantly symmetrical around the hole?

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5 minutes ago, Guppy916 said:

That looks nice and clean , is that some debris at the top of the photo ? Could be not closing properly

Which would be at about 7 O'clock assuming the oil has pooled at the bottom. ✔️

It could be - though it also looks to be away from the seat. The camera does come with a magnetic "bit" that can be attached the end. If is steel is will come out I would think - otherwise its a bit of rag I guess. Not that there is a lot of room to do anything!

2 minutes ago, Badwolf said:

What about cleaning the piston, attaching some very fine wet and dry paper to the top of it. Cut it into a circle and use the piston to polish the valve seat? Then clean off the piston and reassemble. Just a thought... probably a stupid idea!

I do have a couple of spare pistons so could to something - but I am sorting a short drill out to see if that will smooth out the seat. 

The seat of the piston isn't very big - and I am a bit concerned in the three areas highlighted in the picture below.

973188562_Snap_004Markedup.jpg.4f9eef2af3fd1137a5039eb95e61f192.jpg

The red bit is possibly damage? 

Green  also damage? 

Blue looks a bit thin as a seat - assuming the seat is not the big slope and the bit that seems to be at the bottom (of the picture!)

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I don't think they do one small enough to get into the hole - 17mm seems to be the smallest. (Its 9/16" or ~14mm 

Anyway, thinking some more, to recut the seat needs to be done with a lot more care - it needs to be square to the centre line of the hole otherwise it will leak even more!

I think Chris's idea is just to remove any build up from the seat and not to actually do any cutting.

So a light spin by hand with the drill bit more than anything else.

Oh and given the PRV valve has a tapered edge to it, I would think the seat needs to be similarly chamfered.

Edited by Anglefire
Added a bit.
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  yes  its simple design.

pressure is only developed by restriction,  if the pump has no limit in its ability and theres nowhere for the oil to go  pressure will build .

like sticking thumb over the tap and getting a squirt .too much pressure and the thumb gives up.

 

if its  excessive it can blow the block casting gallery feed chamber,  the PRV will be opened against the load on the piston and its spring dumping the excess back to the sump , when the pressure wont open against the spring it closes or modulates to keep the max at a controlled  max pressure

Pete

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My oil warning light came on after about 10 miles, long after the temp gauge was showing normal running temp, but, sadly, I thought it was the alt warning light (!!!) so didn't check the oil gauge at the time. Could be thinning of the oil as it heated up or, as Pete says, a faulty switch. I suspect (hopefully) a faulty switch.

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Got my drill shortened at work today - the cutting edge is not the best - but then probably ideal for just cleaning the seat without cutting it!

Just a bit longer than the plunger itself and goes in easily.

So, gave it a turn (by hand!) and could feel no high spots on the seat and was happy enough that there is nothing really that obviously wrong.

I then measured the spring free length - not exactly sure how that works - but it should be about 1.53" which it seems to be. Comparing the two from the old and new engine sat in the "nut" and the one out of my new engine was arguably a little shorter - but its a knats wing.

Re-assembled and went for a drive. Got it nice and hot and is better than it was - not by a lot, but a bit.

So, I'm going to not worry too much about it at the moment and just drive it and enjoy it.

Snap_006.jpg

Snap_007.jpg

Snap_008.jpg

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Yeah I might do - need to get another copper washer though - this one has been reused about three times now - and they seem too big (hole!) anyway so not sure it actually does anything - and in theory, if it crushes some more, the PRV lifting pressure goes up a bit.

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I've not done anything more regarding the oil pressure apart from go into Solihull to have a look at the 70Year Land Rover fest (Some nice old Land Rover's there as well as some shiney ones.) And a load of different food stalls - we bought some Caribbean Lamb Curry for tea - which we tasted and was lovely :)

Anyway, oil pressure is fine when cold - and stays fine for some while when the engine itself is upto temperature - but then gradually drops as you drive. After about 8-10miles its down to 35psi at 2000rpm at best.

I had another twiddle with the fuel sender (I'll update that post in a bit) - and after it had been sat for probably 15-20minutes, I got my laser temperature thermometer out - and all over the head and block it was something around 90-98'C (block colder than the head - which makes sense, but quite hot I thought, but also even over similar areas - but then it has had time to sink around the engine. 

I then checked the sump temperature and it was over 85'C - which seemed hot? Or is that quite normal? I'm just thinking of the post @rogerguzzi made of Spain.

Oh when driving the engine temperature gauge sits bang in the middle - when with the air temperature up over 26'C.

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Don't know isthe honest answer, but just as a comparison my 1300 spitfire engine reads 83-84 at front and back, 87-88 on the core plugs either side of the distributor. Couldn't get any sensible readings from the exhaust side!

Sump reads 65.

Just Friday got rad back from being recored at local specialist and fitted yesterday because last weekend side mounting decided to part company from top header; been eying some blocked cores through the rad cap for a while so that was the final straw.

Engine fitted with standard 82 thermostat.

David

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Are you sure the hot pressure drop  is not down to the oil spec 

Cant remember what you were using,

I had a good hot drop in the Vit6 using a cheapo  factors brand ,  hot performance sadly lacking 

VR1  and Millers classic have been vastly different , , the 2000 doesnt drop when hot and currently on the millers classic

Pete

 

 

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Pete. I changed the other week from Castrol 20/50 to Millers Classic 20/50. No real difference - though think the Millers is better. Feels better!

32 minutes ago, Mad4classics said:

Don't know isthe honest answer, but just as a comparison my 1300 spitfire engine reads 83-84 at front and back, 87-88 on the core plugs either side of the distributor. Couldn't get any sensible readings from the exhaust side!

Sump reads 65.

Just Friday got rad back from being recored at local specialist and fitted yesterday because last weekend side mounting decided to part company from top header; been eying some blocked cores through the rad cap for a while so that was the final straw.

Engine fitted with standard 82 thermostat.

David

Thanks Dave- my stat is 88 I think? But have a full width radiator and the return on that was about 50'C as it happens Though the rad was only about 60 too - but the stat housing 95ish - but not fresh from a run, so any residual heat would have soaked out.

Sump temperature is interesting. Actually yours might be low (Or is more effectively cooled - as you want the oil to drive any moisture out so most places I've read since my post, suggest should be a bit hotter than the water temperature.

I also understand that most of the oil cooling is via the sump - which is not ribbed and has a chassis rail in front.....

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