ECR Posted July 27, 2008 Share Posted July 27, 2008 Does anyone know at what pressure the oil prv opens ? Now I have a gauge that works it becomes interesting .... Ex Chairman Roger Link to comment Share on other sites More sharing options...
Alba 7 Posted July 27, 2008 Share Posted July 27, 2008 Roger, Not sure if this any help, but my Stack never shows more than 73 psi. This is on a caterham wet sump, standard engine other than D2H injection. HTH, Nick. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 27, 2008 Share Posted July 27, 2008 Roger, I adjusted mine using small washers under the nut end of the spring so that the normal running pressure with engine up to temperature was 60psi which, I assume, is when the prv opens up. I assume you're dry sump and using the CC bell tank and original oil pump, rather than a separate Pace pump. Paul Link to comment Share on other sites More sharing options...
ECR Posted July 27, 2008 Author Share Posted July 27, 2008 It definitely looks like mine is sticking then as it would now be quite easy to hit 100psi with coldish oil. Given that my new gauge only reads upto 100psi I could well be blowing the back off it soon ! This could well explain a slight weep from one of the cam shaft oil seals which I have been unable to stop. I would have expected the prv to operate at more than 60psi though .... although I can't really fault the logic of setting it at that. (Yes, I use the stanadard pump on the pressure side). I wonder how long it's been running like this and what sort of pressures it has been seeing .... and if overpressure has contributed to the failure of the original sender/gauge. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 27, 2008 Share Posted July 27, 2008 Cripes! It would almost certainly explain your leak and I wonder whether your crank rear seal has been under stress as well. The valve is either stuck shut or its been loaded up with spacers to compress the spring. SBD do a fibre prv piston which, they claim, is less prone to jamming if a foreign body gets in to the valve as it will dig into the fibre. I'm not convinced but I had one until I went Pace dry sump. People like SBD recommend 60psi hot at 2000rpm plus and there doesn't seem to be any good reason to go any higher as the cam followers should have gone quiet by then, if you still have hydraulic lifters that is. Link to comment Share on other sites More sharing options...
F355GTS Posted July 27, 2008 Share Posted July 27, 2008 Roger, mone is set to 60psi (hot) with washers too, I did have one stick a while back which showed 100psi + on the stack, removed the PRV and cleaned it up and it worked fine again Mark Link to comment Share on other sites More sharing options...
ECR Posted July 27, 2008 Author Share Posted July 27, 2008 Mine's a Swindon supplied fibre piston which I had to skim down to stop it sticking. Perhaps it's swelled up again... I'll be investigating tomorrow and will set it at 60psi hot as you both have done. Thanks for the input. Ex Chairman Roger Link to comment Share on other sites More sharing options...
ECR Posted July 28, 2008 Author Share Posted July 28, 2008 I have just replaced my Swindon valve with a (cleaned and polished) OE one and the problem is solved. I was a little surprised as the Swindon part was very free in the bore (it fell out when I undid the nut) and the bore and the piston were in good condition. I can only deduce that the Swindon spring (which is a smaller diameter although the same length) is more powerful than the standard one. I have had problems over the years (probably not real but indicated by that pesky sender gauge set up) with relief valves and it could be that at some time a stronger spring was supplied to overcome an imagined problem … Anyway, it’s now popping open at about 70psi which is fine Ex Chairman Roger Link to comment Share on other sites More sharing options...
Swiss_Tony Posted July 28, 2008 Share Posted July 28, 2008 The fibre/plastic ones are very prone to sticking and not always in the desirable pressure range 😳 The oe ones are much better. iro 60psi is spot on by the way 😬 Its unlikely that the cam seal is leaking due to the oil pressure as its not under pressure. Its worth changing the seal again to make sure but its also not unheard of for them to leak oil around the front cam bearing cap or most likely down the bolt thread as the cams are filled with oil via the gallery in the head and the oil creeps up the threads. If its still leaking with the lower oil pressure its worth re-sealing the threads on the cam pulleys. I have sometimes had to resort to a dab of sealant on the threads to cure them. James Su77on Se7ens Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 28, 2008 Share Posted July 28, 2008 Pleased to here its solved Roger. I agree with James re the sealant on the cam pulley threads - I always add a a dab of loctite, more as a sealant than as thread locker. Link to comment Share on other sites More sharing options...
ECR Posted July 28, 2008 Author Share Posted July 28, 2008 I've never thought of sealing the bolt threads, but if they are through to the oil gallery then it's obviously a good idea. I think that the cam seal is pressurised as there is a small drilling at 6:00. This would pressurise the back of the seal and make sure it seals against the cam. I suppose that it could be just a drain .... Edited by - ECR on 29 Jul 2008 10:00:27 Link to comment Share on other sites More sharing options...
Mavic82 Posted July 28, 2008 Share Posted July 28, 2008 Now you all have me worried. Mine runs at a steady 3.5 to 3.6 bar when up to temp at cruising speed which now seems low, although both this engine and my previous one read the same. Should I add some washers? Basing the reading on the VDO gauge. Cheers Guy Link to comment Share on other sites More sharing options...
ECR Posted July 28, 2008 Author Share Posted July 28, 2008 Based on my recent experience the FIRST thing to do is verify your VDO setup is reading correctly by plumbing in a mechanical gauge and comparing. I'm sure you can borrow one from work ..... Ex Chairman Roger Link to comment Share on other sites More sharing options...
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