Support Team Shaun_E Posted June 6, 2006 Support Team Share Posted June 6, 2006 I've had a persistent oil leak for the last 2 or 3 months from my dry sumped K-series. I've tried tightening every joint I can find. I did find that a couple of the allen bolts holding the conning tower to the bellhousing were loose and oil had escaped there so I tightened those up. There is a more significant leak though from the front of the engine which I haven't been able to locate the source of. Over the last few weeks the oil pressure at idle has been steadily dropping and when hot is now about 8 or 9 psi. This is clearly not right and I don't want to destroy the engine by continuing to run it. Although the oil level did get quite low at one point I don't believe the engine has suffered oil starvation although I can't completely rule it out. I have been using Mobil 1 0W-40. So the question is "What do I do now?" Is it just a case of removing and stripping the engine or are there some other things I can check first? Is the oil pump a likely point of failure and if so can it be changed in-situ? I have just fitted a new presssure sender and it reads the same as the old one - it's a Stack dash (the sender is made by VDO). Yellow SL #32 Link to comment Share on other sites More sharing options...
Bozz Posted June 6, 2006 Share Posted June 6, 2006 When at Oily's place earlier in the year having a head gasket job done we (he) replaced the crankshaft front oil seal on my K which was leaking slightly. This is on the outboard side of the oil pump casing. I suppose (although I'm not sure) that if this was leaking badly oil pressure could be lost. Hopefullly someone will come along shortly who will confirm or otherwise. Bozz My Chocolate Orange here Link to comment Share on other sites More sharing options...
oilyhands Posted June 6, 2006 Share Posted June 6, 2006 Shaun, Leaks from the front are normally the cam seals or the front crankshaft seal. If you have falling oil pressure then it could be bearings and it needs looking at sooner rather than later. It's not unknown for the Caterham scavenge pump to get behing the pressure pump in terms of delivery and if your oil level is low that could give you a oiling problem. Was you gold pump in good order/new... oily Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted June 6, 2006 Author Support Team Share Posted June 6, 2006 Dave, I will call you in the morning. I think I need to replace the bearings and it wouldn't hurt to fit a new crankshaft oil seal. I think I'll get a new oil pump as well. We checked out my gold pump, which was fairly new, when we built the engine and although there were a couple of scratches on the rotor it was OK. I hope I don't need a new pump. The cam seals were replaced when we built the engine as the old ones were leaking a bit. The leak is defintiely not at the top of the engine so I suspect the crankshaft seal is more likely the culprit. Shaun Yellow SL #32 Link to comment Share on other sites More sharing options...
Mark Durrant Posted June 6, 2006 Share Posted June 6, 2006 Shaun How accurate is your oil pressure guage 🤔 Is it mechanical if not it could be the sender Mark D Comp Sec Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted June 7, 2006 Author Support Team Share Posted June 7, 2006 Mark - its a Stack unit and I fitted a new sender yesterday to be sure. I was keeping my fingers crossed but it was really just wishful thinking. Yellow SL #32 Link to comment Share on other sites More sharing options...
Jason Plato Posted June 7, 2006 Share Posted June 7, 2006 how olds the engine Shaun ? . Its unusual to have problems with the bearings on dry sump unless you let the oil run down to a low level ?. As said above I would take it aprat and find the cause before any more damage is done ☹️ Dave Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted June 7, 2006 Author Support Team Share Posted June 7, 2006 Engine was only built 7 month's ago ☹️. It must have been losing oil quicker than I thought - I had to put about a litre in when I checked it the other day. I know I should have checked it more frequently - angry with myself Will get it stripped and checked and hopefully back in the car for Loton Park. Bummer is that we were due to go for a weeks holiday in Scotland in it, leaving on Saturday - no chance of fixing it before then. I'm a bit worried about the scavenge pump now. It had ingested something when it was on the old engine but a very slight score on the rotor was easily polished out - should I replace it? Yellow SL #32 Link to comment Share on other sites More sharing options...
Jason Plato Posted June 7, 2006 Share Posted June 7, 2006 Titan who make the pump offer a repair / overhaul service for the pumps . here is their website and contact details they are a nice company to deal with Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 7, 2006 Share Posted June 7, 2006 There are two things being considered here... 1. Leaks and possible running with low oil level 2. Low oil pressure Low oil level will only result in low oil pressure if the pickup ends up drawing air instead of oil. Dry sump setups are inherently more resistant to this sort of issue because the tank is taller and narrower than a shallow wet sump. If the oil level gets so low in a dry sump setup that air gets supplied to the pressure pump, the consequences are worse with a dry sump - there really isn't any oil to deliver, rather than momentary surge. If you have been suffering from such low oil levels that air has been delivered to the oil galleries then you will likely have a catastrophic failure on your hands unless you don't run your engine again and get it investigated and fixed. The low oil pressure itself is a different matter and your description of symptoms does not necessarily tie in with impending catastophic failure. A gradual reduction in idling oil pressure is not the best indicator of engine health. You haven't described whether it is hot or cold oil. Ambient conditions have been getting hotter. At what revs does full pressure establish itself. The oil pressure pump is a very simple device. If the problem was the scavenge pump, the engine would already have blown up. The pressure pump rotor is sintered and can crack. Pressure is also determined largely by the pressure relief valve. The PRV is easily inspected. Your leak at the front of the engine could also be... the oil delivery union between the sump and the pressure pump - the steel tube with two O-rings. This can sometimes be too long, preventing the sump from bolting up tight. This can sometimes need to be ground down shorter, so that the O-rings can exert their authority and seal properly. Without this, not only will the sunmp leak, but there is a chance the union could allow a small seepage of air to reach the pressure pump. Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted June 7, 2006 Author Support Team Share Posted June 7, 2006 Peter - thanks for some clear explanations. I will try and clarify things. 1. Possible running with low oil level: I would be surprised if the pressure pump has been sucking air, even with it running a litre of oil less than recommended. I can't however rule this out and, unless another obvious cause of the low oil pressure is found, will take the advice to take the engine apart and get it fixed. 2. Low oil pressure: All pressures quoted are when hot i.e. oil temperature over 70 degrees. I realise that ambient temperatures have increased recently but the pressure drop over time has been siginficant at the same oil temperature - I have however noticed that the idle speed has dropped a couple of hundred rpm (don't know if that is significant really). It takes about 2000 rpm to get 30 psi and then 4000+ to get to over 50 psi. The oil pressure at 4000+ has also had a corresponding decrease and at 70 degrees is around 50psi. I need to check the other possible low oil pressure causes you suggest. a) where is the PRV and what do I do to check it? b) can the pressure pump be removed with the engine in-situ? c) I'll check the steel tube - does it have to be ground down accurately? How do I check? Cheers, Shaun Yellow SL #32 Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted June 7, 2006 Author Support Team Share Posted June 7, 2006 Having chatted with Oily, I will be removing the head to check the big ends. I will also check the other things Peter mentioned and probably get the scavenge pump refurbished (thanks for the link Dave J). Yellow SL #32 Link to comment Share on other sites More sharing options...
oilyhands Posted June 7, 2006 Share Posted June 7, 2006 Shaun, before you do this, tweak the idle adjustment screw to get the idle to 1000 RPM, then check your pressure. Oily Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted June 7, 2006 Author Support Team Share Posted June 7, 2006 Dave - I'll do that but I did use the throttle to raise the revs to about 1200 and the oil pressure was still only about 11 or 12 psi Yellow SL #32 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 7, 2006 Share Posted June 7, 2006 What pressure are you expecting at hot idle? What did you have before? Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted June 7, 2006 Author Support Team Share Posted June 7, 2006 When it was first built, hot idle was 28 to 30 psi - admittedly in the winter when I rarely saw much more than 60 degrees oil temp. This has gradually reduced over the last few weeks to less than 15psi and then this week has dropped steadily to now be 8/9 psi. At higher rpm I used to get over 60psi but now get about 50psi. The engine feels and sounds rougher than it was for the first few months (coincidence?). I have done 3 trackdays and 3 sprints in the last 3 months. At the first trackday I don't remember the low pressure warning light coming on (set for 15 psi). Yellow SL #32 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 7, 2006 Share Posted June 7, 2006 c) I'll check the steel tube - does it have to be ground down accurately? How do I check? It doesn't need to be accurate. If it is too long, the sump/block join will leak even if the bolts are tight. Link to comment Share on other sites More sharing options...
Mick Day Posted June 7, 2006 Share Posted June 7, 2006 I have however noticed that the idle speed has dropped a couple of hundred rpm (don't know if that is significant really) Shaun Sorry to hear of your problem. My only experience of a seized engine started with low OP & then a lower idle speed as the engine "tightened up". When it was stripped one big end bearing shell had managed to destroy itself completely. Needed new rods & crank & I was lucky not to destroy the engine case. Not a K series I hasten to add. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now