New engine failing oil pressure - it's a long story

[Tonycaterham]

I have just had my engine rebuilt by a very reputable engine builder which involved new pistons liners etc etc. The engine is 1800 K series running Caterham dry sump with gold pump. I ran the engine in for over 300 miles and all was well. Oil pressure was high around 8b bar when hot under load and 2 bar at idle. After 300 miles changed oil.(Caterham Motorsport oil and new filter).

 

Next day arrive at Rockingham for 7 club track day last weekend and after taking it steady for a few laps suddenly on the main banking noticed the oil pressure start to fall fairly rapidly from 8 bar I hit the kill switch whilst it was still falling then around 5 bar, so did not loose oil pressure (according to electric guage) and oil pressure warning light with high pressure switch did not come on

Back in the pits found the dip stick on the dry sump top had come unscrewed and a little bit of oil had sprayed out the top. Several people who had gathered to offer assistance (thanks Dave Nelson) . Put dipstick back in put a little more oil in just in case and started her up. Pressure went up to 8 bar again under load revving to about 4000rpm. All was fine except Gold pump seemed to be making an odd rumpling noise. Then suddenly the hose from top of dry sump tower to the catch tank blew off resulting oil spraying oil everywhere resulting in a big clean up (thanks Mav and co ) and orry to Dave Nelson who nearly got hot oil in his eye! On investigation I found a piece of plastic in the hose to the catch tank effectively virtually stopping the air/oil venting to the catch tank. the piece of plastic was not engine related and hose had been at home, so how if ended up in the the will remain mystery. Put everything back together and started it up pressure went to 1 bar on idle and 4 bar underload, Gold pump quiet and enginge sounding sweet. More oil into engine to be on safe side (could blow excess into catch tank now!). Checked with Bookatrack mechanics who said 4 bar was fine left engine running for several minutes all ok. So, ventured out onto track for couple of gently laps and all was fine, so started to open her up. She was all right for two laps but then under load noticed oil pressure slowly started to drop to 2 bar over the space of about an couple of laps so not risking it slowly dropping any lower, slowed right off and came in.

 

on inspection seemed to be a lot of oil on underside of car which was not there before last run and on getting it home only got just over 5 litres of oil out of engine. Good news though, oil clean no shiny bits in the oil at all.

 

I can only deduce that the blocked hose to the catch tank meant I was running a highly pressurised engine which although seems odd as some would say itb is not possible that this had a direct impact upon the oil pressure, but all the events seem to point to this. Now really concerned about falling pressureand anothing very large bill.

 

The dry sump equipment had been working perfectly on my old engine before I put in on another modified second hand engine ( which had done 10,000 miles) which unfortunately ran a main bearing at Oulton Park trackday in July after having only done 30 track miles causing the full rebuild.

 

 

Any thoughts on what to do next? I accept that the only option may be to take engine out and back to the person who built it but he is booked up to Feb 09! Is there is anything else I can do or look at then pleased to hear your thoughts. The engine is half out as I type.

 

I do NOT for one second believe it is a problem with the build. I believe it all related to running an engine that could not vent.

 

Any thoughts from those who really know their stuff would be appreciated before I pour even more money into this car which I love but is testing me to the limit at the moment. ☹️

 

 

Tony

 

L7 EVL

[Julian Thompson]

Tony you have my sympathy. It's not a good feeling when this kind of thing happens.

 

Bearing in mind my recent experiences I would say that you need to liase closely with your engine builder. He might be booked up but it's not like you need to actually have to rebuild the engine so it's just advisory work at present, surely? It would seem to me that you need to :

 

1) Check your oil pressure measurement system carefully to ensure validity of your readings.

 

2) Remove, strip and inspect your scavenge pump. I would say this irrespective of working condition previously. My scavenge was functioning *fine* on my old engine and went back to the manufacturer for inspection as a precautionary measure. It was knackered.

 

3) Remove, strip and inspect your oil pump. I would say this irrespective of whether this was replaced during the new build. Stuff can be faulty.

 

Good luck!

 

[Rob Walker]

Tony,

 

Its sounds like your scavenge pump is not working properly and that excessive oil is being held within the engine and hence you are running low on oil after a couple of laps.

 

Apart from the obvious, like checking all the pipwork is correct and not obstructed you could check that the drivebelt and tensioner are working correctly. It may also be prudent to send the pump back to Titan and have it overhauled.

 

If there are no shiny metal paticles in the oil or the oil filter this is a good sign. however to be sure you could remove the big end cap from number 4 rod and have a look at the bearing.

 

Good luck

 

Rob

 

Edited by - Rob Walker on 25 Oct 2008 12:17:24

[Jason Plato]

and check the gauze is not obstructed in the suction pipe from the sump pan.

[Tonycaterham]

Guys,

 

Thanks for the responses so far, I'll pull the engine out this weekend and start looking into the areas suggested.

 

A few questions,

 

How do I test my guage /sender for accuracy?

 

The pump was pronounced good by my engine builder, but prepared to replace.

 

The reference to Titan means I presume the Gold pump is made by Titan.

 

Rob, excuse my lack of knowledge but why bearing 4 ( i presume at the rear and therefore furthest from the pump? Can I simply remove cap, look at the bearing and if OK simply replace and tighten up?

 

This engine now stands me at nearly £6k given the original purchase and subsequent rebuild so a few more components,fitting and removing engine a couple of times over the next few weeks/months I can live with....just.

 

 

 

Tony

 

L7 EVL

 

Edited by - Tony7 on 25 Oct 2008 16:55:55

[Julian Thompson]

Don't remove the engine yet Tony.

 

Make sure the wiring is perfect to the guage and sender and that the sender is not suffering from vibration. If the sender is mounted direct to the engine without a remote it is easy to get poor guage performance. Also you want to be looking at the way the sender is earthed since I have seen many an unsatisfactory ground which can give bad readings at higher rpm due to vibration. Obviously you can't test for vibration without running the engine so if a careful exploration of the setup does not yield a fault you may be forced into checking the scavenge and then oil pump anyway in order to have the confidence to run the engine again.

 

Surely you can remove the scavenge and internal oil pump with the motor in situ?

[TomB]

Titan refurbished my purple scavenge pump and fitted new rotors for about £80-90 a couple of winters ago. Very pleasant company to deal with.

[Tonycaterham]

Tom,

 

#Googling' Titan but struggling to find an address can you help?

 

 

 

Tony

 

L7 EVL

[Tonycaterham]

Julian,

 

I have checked the wiring at it all looks Ok have checked it all with a volt meter as well. Having drained the engine of oil last wweek there is now a small pool on the floor at the rear of the engine around bellhousing area. I wonder if the rear oil seal have gone and deposited oil in the bellhousing which is now slowly leaking out. Like you I've have had engines in and out so several times, so apart from time consuming not too worried about taking it out again, if I have to.

 

Thanks for the advice ....it really helps!

 

Tony

 

L7 EVL

[Allen Payne]

I thought the oil pressure relief value on the K-series limits the pressure to about 5bar. If you're seeing 8bar then maybe you need to look at the accuracy of the gauge.

[Rob Walker]

Titan Motorsport Manufacturing 01480 474402.

 

You are correct number 4 big end is the last to be supplied so usually the first to become damaged in oil starvation .

 

Don`t panic! I certaily would not start pulling the engine out at this stage. Sort out the scavenge problems and all may be well, if its not then think about looking further.

 

What you have to understand is that the level of oil contained within the belltank can quickly fall if the scavenge is not working effectively as sufficient oil is not being removed from the engine and the oil pressure pump which is driven directly off the crank keeps supplying oil . It then depends on how you have run your pipework back to the block that determines what level the pressure pump will start to see intermittant oil supply . Also with a large volume of oil held within the block this quicky gets aireated which will also result in reduced oil pressure.

 

 

 

If you are worried about the oil pressure gauge then fit a mechanical one for more reliable results.

 

Rob

 

Edited by - Rob Walker on 25 Oct 2008 18:37:54

[Willie.]

Have you any idea of oil temps during this all?

 

You should be able to see the rear crank oil seal through the hole in the bellhousing near the starter, and the same on the other side. Shine a torch in. If there is any gap at all between it and the block...its out. You can use a screwdriver to wiggle it and see if its loose.

 

It puts oil everywhere when it throws it, espically around the starter area.

 

Hope you get it sorted.

 

Willie

[Tonycaterham]

Rob,

 

Thanks for the comprehensive responses.

 

Do you think running the engine in a pressurised state for 300 miles is likely to have damaged the oil pump, the scavenge pump or blown a seal? Or is the engine likely to have tolerated breing pressurised to this level?

In terms of pipe work it is as per Caterham suggest; one runing from the front of the dry sump to the bottom of the dry sump bell tank and the other from the scavenge pump to near the top of the dry sump tower.

 

 

Tony

 

L7 EVL

[Tonycaterham]

Willie, I take the startermotor out and have a good look tomorrow. I do not have an oil temperature gauge but the water tremperature was around 70C.

 

Tony

 

L7 EVL

[Gridgway]

A couple of thoughts...

 

number 1...8 bar is surely not right, that is 120 psi, far too much. You must have a guage or pressure problem there. If it's the releif valve, that's an engine build problem.

 

number 2...you are seeing lubrication problems and your previous engine let go with lubrication problems. Is that the same effect from the oil system installation? What common components are there?

 

Hope you get it fixed without too much further cost.

 

Graham

[Peter Carmichael]

Agree with Gridgway.

 

From what I've read the blockage is the only fault.

 

8bar is far too high.

 

The pressure relief valve is set closer to 4 bar. That holds the difference between the sump pressure and the inlet (dry sump tank) pressure. The gauge measures gallery pressure to atmosphere. 8 bar implies 4 bar pressurisation of the dry sump tank. The scavnege pump would have been doing a good job of emptying the crank case until the volumetrics of working against a pressure differential prevented it from being able to shift any more oil. At this point the engine would fail to scavenge. Likely also that the pressure pump's charge would divert totally around the pressure relief valve and no new oil flowing into the galleries.

 

You need to make sure all your seals are intact. You need to make sure your big ends are intact. You need to make sure the lubrication system is now functioning properly.

 

I think any approach of "I think I may have got away with it" is wishful thinking.

[Jason Plato]

you will see 8 bar on the guage if you rev the engine when the oil isnt warm. This is because the oil pressure relief spring / valve cant cope and is fully open yet the pressure is still 8 bar. When you start the car from cold on the driveway the guage reads 7/8 bar. the reduces to 3.9 bar when up to temp.

 

If you read on Tony then sees 4 bar . This is probably after the oil has warmed up ?

[oilyhands]

Rob,

 

Number 1/2 is the first end to suffer starvation because it has a shorter run from the pump and receives any air more quickly.. In my experience it is pretty much always these that suffer most damage.

 

I would fit a capilliary/mechanical gauge to the engine and run it up to temperature to see what your true oil pressure is. Following a diagnosis with 100% accurate pressure readings you can probbly decide what to do next.

 

Oily

[Beelzebub]

My mains were nadgered in exactly that order due to oil surge on the std wet sump.

 

D.

 

Edited by - Davesport on 27 Oct 2008 08:36:10

[Tonycaterham]

Thanks for all the responses.

 

I only saw 4 bar on the gauge once the blockage in the hose to the catchtank had been removed, prior to that I was seeing 8 bar under load even when engine was hot and for over 300 miles during the running in period.

 

The fact that it is dripping oil from the bellhousing even now I have drained the oil would seem to indicate that the rear oil seal may have 'blown' ?

 

Given that the lead time for the engine to go possibly go back to the builder for investigation I have plenty of time to investigate myself I am prepared to 'pull the engine out'

So, suggested course of action for your thoughts please;

*arrowright*Remove engine check/replace rear oil seal.

Any other seals I should check?

 

*arrowright*Remove all bearing caps and inspect bearings (presume if they are OK

simply put shell back and re-tighten bearing caps?)

 

*arrowright*If all OK (or even it not) fit mechanical Oil Pressure Gauge and

restart engine.

 

The car is used mainly for track days so not concerned if it spends the next few months in bits!

 

 

 

 

 

 

 

Tony

 

L7 EVL

[oilyhands]

Depending on the damage found it may be a relatively quick fix, I.e. possible in a day, if so you may find the turn round a bit quicker.

 

Oily

[Tonycaterham]

Dave

 

YHM

 

Tony

 

L7 EVL

[david nelson]

I would ask the engine builder to have a look ASAP. If its only just gone in he should be more helpful than feb 2009? Who was the engine builder?

[oilyhands]

The head has to come off to lok at the big end caps and as the engine is a ladder frame design, there are no main bearing caps, the engine sandwich has to come apart..

 

Oily

 

 

[Rob Walker]

Oily,

 

I have two K`s in my garage that have both suffered oil starvation . Both have damage limited to number 4 big end shells and crank pin only. Hence my rational that when the oil flow is interupted the last in line gets zilch.

 

Rob