Low oil pressure

[boardinscotland]

Hi there

Have been reading all the forums and have finally joined. Was wondering if anyone has any ideas. I have bought a tuscan (finally after drooling over them for a long time) and have a slight worry about the oil pressure. Once the engine is hot at 75 deg or so on idle it shows about 9-12 psi which i have told is what is to be expected with the speed sixes. All is fine on normal revs, however if i get stuck in traffic or in town oil temp goes up to 87-94 deg which is not unexpected however oil pressure drops to 1-6 psi on idle. When it is this low you can hear a knock from the top end presumably from oil not getting there. At the moment the speed 6 is running on 5 - 40 w. Any suggestions. Should i refinance my house etc if it serios.

Cheers in advance

Edited by boardinscotland on Sunday 13th January 23:46

[Fume Troll]

boardinscotland said:

Hi there

Have been reading all the forums and have finally joined. Was wondering if anyone has any ideas. I have bought a tuscan (finally after drooling over them for a long time) and have a slight worry about the oil pressure. Once the engine is hot at 75 deg or so on idle it shows about 9-12 psi which i have told is what is to be expected with the speed sixes. All is fine on normal revs, however if i get stuck in traffic or in town oil temp goes up to 87-94 deg which is not unexpected however oil pressure drops to 1-6 psi on idle. When it is this low you can hear a knock from the top end presumably from oil not getting there. At the moment the speed 6 is running on 5 - 40 w. Any suggestions. Should i refinance my house etc if it serios.

Cheers in advance

Edited by boardinscotland on Sunday 13th January 23:46

That does sound a little low to me....

Cheers,

FT.

[Daftlad]

What is your hot idle speed, I suspect about 750 RPM? It should be 900-950.

[boardinscotland]

Yeah the hot idle speed is actually about 700 RPM. When sitting in traffic i usually try and touch the accelerator to keep the idle up at 900rpm or so.

Thanks will look into it .

[tamore]

also, it might still have the old style pressure sensor. they misread and leak in some cases. have it changed for the new one if you haven't already done so.

[s6boy]

If sitting for long periods in traffic I bring the revs up to about 1200 for a few seconds where oil pressure rises to between 25-30 psi, not sure if this does any good but pressume it helps get oil to the top end and certainly can't do any damage.

[bosscerbera]

Nothing will live for very long at those kind of pressures. <10psi at hot idle is not unusual for a Speed Six.

30-40psi at hot idle is what's required and sustaining 10psi per 1000rpm is what you want the rest of the time. No Speed Six achieves anywhere close to this kind of oil pressure.

Healthy AJP8s achieve this all the time on the road and it only starts to fall off with severe track use (my ten year old 50,000 mile 4.5 falls to around 50psi at full chat by the end of a 30 minute trackday session). My Cerbera is 8 years beyond its warranty expiring. Compare the AJP8's reliability record to the Speed Six. These same stats apply to most production engines ...which like the AJP8 also don't suffer from frequent "rebuilds".

[andyoleary]

Phil,

Could you assume that a hot idle (~975rpm) at around 22psi demonstrates a healthy engine or shouldn't this be assumed? Does good pressure mean good flow/penetration too?

Andy

[bosscerbera]

andyoleary said:

Could you assume that a hot idle (~975rpm) at around 22psi demonstrates a healthy engine or shouldn't this be assumed? Does good pressure mean good flow/penetration too?

What oil/grade? What oil temperature is that pressure seen at? 22psi when warm is certainly at the better end of the Speed Six scale. The second question is deceptively 'simple'. The short answer is no, not in the case of the Speed Six. The higher the reading the better though.

One area where TVR was thorough though (and it did make us laugh when we found it) is that the Tamora/T350/Sagaris dash has a "High Oil Pressure" warning. It's set at 100psi. I bet nobody else has ever seen that! We used to get it when the engines were cold (the first Wilder oil pump was a bit of an animal). As one of the engineers said about oil pressure at the time: "I'd rather be looking at it than for it".

[holmsie]

In that case, it would maybe be interesting to know what kind of oil pressures rebuilt engines are producing, and compare those to original TVR speed6 and the new Wilder engine pressures (or does the new oil pump on the Wilder contribute to the difference more than the engine itself?).
Can anyone with a recently rebuilt engine tell us what pressures they see?

[andyoleary]

bosscerbera said:

andyoleary said:

Could you assume that a hot idle (~975rpm) at around 22psi demonstrates a healthy engine or shouldn't this be assumed? Does good pressure mean good flow/penetration too?

What oil/grade? What oil temperature is that pressure seen at? 22psi when warm is certainly at the better end of the Speed Six scale. The second question is deceptively 'simple'. The short answer is no, not in the case of the Speed Six. The higher the reading the better though.

One area where TVR was thorough though (and it did make us laugh when we found it) is that the Tamora/T350/Sagaris dash has a "High Oil Pressure" warning. It's set at 100psi. I bet nobody else has ever seen that! We used to get it when the engines were cold (the first Wilder oil pump was a bit of an animal). As one of the engineers said about oil pressure at the time: "I'd rather be looking at it than for it".

Hi Phil,

Oil temp when nice and warm is normally around 75/80C for this idle pressure mentioned. 15W/50 Mobil1 motorsport I think although I do top up with Shell Helix Ultra fully synth 5W40. The 2nd question was intentionally simple as it's something I have often wondered, especially with the often mentioned oilways "issues" within the design of the SP6...

Thanks for the reply,

Andy

[boardinscotland]

Hi Andy

I assume by your last comment you have a speed 6 and run it on 15W 50. I was recommended to run it on 5W 40 but have been now thinking to go thicker due to this low oil pressure when on hot idle.

Thanks for your discussion. Has got me thinking.

Greig

[andyoleary]

Hi Greig,

My Tuscan is over 6yrs old with 36K miles on the clock and no serious engine work (yet ) and has pretty much always been serviced by Fernhurst Motors. Fernies use 15W50 oil during their service work. I think Bryan feels this oil is better suited to "older" engines rather than the thin 0W40 Mobil, for example. There are a lot of opinions on which oil to use and I think a lot of consideration has to be given to the particular engine in question. However, the "opie oils" thread is handy reading. It's always a good idea to talk to whoever looks after your car for you (or who has some history on it).

Regards

Andy

[boardinscotland]

Hi Andy

Thanks for your reply. My Tuscan is one of the early ones too (W reg). Has 22300 miles on the clock. Think I will be looking at putting the heavier oil in too especially to see if I can get the old pressure up a little. The guys that I bought it off stay by the book of the 5W 40 but my old man is a mechanic and has numerous old and sports cars and is of the opinion it needs heavier oil. As u said each engine is different so think I will give it a shot.


Cheers Greig

Edited by boardinscotland on Tuesday 15th January 23:37

Edited by boardinscotland on Tuesday 15th January 23:40

[scooterscot]

As has been said earlier the idle speed should be at least 900 rpm or you will see a big drop in the oil pressure. The pressure senders even the new modified one's are not the best, if you are concerened about your oil pressure have it checked with a proper hydraulic pressure gauge. It is also worth taking out the gauze filter in the catch tank and making sure it is clean as we have seen a few with silicon in them. Dont allow the engine to top end knock keep the pressure up with use of the throttle rather than let the head go short of oil as cam/fallower damage can happen very quickley. We use 10w 40 oil in the straight six as directed by John Ravenscroft.

[Andy11]

Hi, don't think you need to worry, but I would change the oil to 10w40 and replace the oil pressure sensor, just changed mine and pressure has increased by 5 psi. Oil pressure should be 1psi to 100 revs, your temp is fine also, if it gets towards 100 and does not control it there could be a problem. Also get your idle speed increased, this will increase the oil pressure at idle.