Grim Reaper Posted July 15, 2003 Share Posted July 15, 2003 Out at the weekend,everything seems to be fine (managed to escape any serious damage after a sump/ground clash the day before)when suddenly the oil temp warning on the stack dash comes on..Oil Temp 130 deg C!! Water temp around 77 deg C (have a 76 deg thermostat) no strange noises or smells. Continued on..Oil temp varying between 130 and 140 on the gauge,most often at 135,water temp still at 76-85 degrees depending on traffic/speed. Started the car up again today,oil temp rises very quickly on the dash,up to 90 within 4 minutes,very erratic readings,water to about 70 by this time,smooth rise. Took a dipstick drop test and the oil seems quite cool to touch,certainly nowhere near boiling water temp.Oil filter is warm to the touch but not so hot that I can't keep my hand on it for a while. Could this be a sender problem? What else could be causing the oil temp to rise SO quickly? Since the temp stayed within a 10 degree window during a 50mile trip home (with me sweating in the cockpit with the heater on full blast to try to help keep things cooler)I personally don't think there is anything wrong with the oil,just the sender giving duff info (or the dash interpreting it wrongly). Any comments? Link to comment Share on other sites More sharing options...
V7 SLR Posted July 15, 2003 Share Posted July 15, 2003 What sender does the Stack use? If it's the standard Caterham one and not a Stack version then I suspect that. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
Grim Reaper Posted July 15, 2003 Author Share Posted July 15, 2003 The senders are Stack supplied,same type for both water and oil. Resistance at room temp was about the same (769 water 787 oil at indicated 23 and 28 degrees on the dash) I'll be checking them again in a moment to see what the difference is when it's warmed through. Link to comment Share on other sites More sharing options...
Nick M Posted July 15, 2003 Share Posted July 15, 2003 I think Stack use VDO senders don't they ?? Link to comment Share on other sites More sharing options...
Grim Reaper Posted July 15, 2003 Author Share Posted July 15, 2003 The senders are brass,2 connection,Type number ST764. As detailed in DT's catalogue in the Stack section under Fluid Temperature sensor 0-150 degC. At £30 a shot it had better last more than 3 weeks!! Link to comment Share on other sites More sharing options...
Chris W Posted July 15, 2003 Share Posted July 15, 2003 Grim If the senders are identical why don't you swap over the connection to each one. Probably easiest to do this at the Stack unit unless the senders happen to be near each other. So your oil temp gauge will temporarily be the water temp gauge and vice versa. If the problem swaps over too, ie: the water gauge now reads incorrectly and the oil temp gauge is OK, you have a faulty sender. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Grim Reaper Posted July 16, 2003 Author Share Posted July 16, 2003 That's fine unless the oil is really getting that hot. Readings I took a little later last night (maybe too late as things had cooled down more than I wanted them to) gave 605 ohms at an indicated 40 deg C for the oil and 523 ohms at 35 for the water. This means the senders reduce resistance as they get warmer but the water sender is educing more than the oil for a given temperature change,so I suppose the next thing to do is watch the oil sender resistance as the engine warms up to see what it is doing. I really need to independently check the oil temp some other way to confirm what the dash is telling me. would taking a temp reading off the filter housing be a reasonable mirror of the oil temp? Link to comment Share on other sites More sharing options...
Marius Posted July 16, 2003 Share Posted July 16, 2003 I had a similiar problem some time ago. STACK showed 130°C ++ and I re-checked with a temp-laser-gun into the dry-sump-tank (will take you 3 seconds to do, I´m sure someone herre has one to spare). STACK was spot on unfortunately, have an oil-cooler problem now... ☹️ Marius Link to comment Share on other sites More sharing options...
scooby dooby doo Posted July 16, 2003 Share Posted July 16, 2003 what's the spec 🤔 is it a wet sump K 🤔 is there too much oil in there 🤔 HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Grim Reaper Posted July 16, 2003 Author Share Posted July 16, 2003 It is a wet sump K,the temperatures were OK on Saturday and Sunday morning, even in traffic jams at Midday on Hot Sunday. On the trip home however,the warning light came on during normal driving. Too much oil?? It's been alright for two weeks since last oil fill,pressure seems good at around 60psi under power (castrol GTX 15W40 for running in)no funny noises,no oil being lost. It was running at around 83 deg C all last week. Link to comment Share on other sites More sharing options...
Marius Posted July 16, 2003 Share Posted July 16, 2003 Under normal (traffic, city, etc.) circumkstances a healthy K would never reach 130°C oil temperature, no matter if wetsump or not. You only get these readings on race tracks and if there´s something VERY wrong. So faulty sensor or big problem ??? Check it with the temperature-gun, it´ll give you peace of mind. Marius Link to comment Share on other sites More sharing options...
scooby dooby doo Posted July 16, 2003 Share Posted July 16, 2003 agreed. something VERY wrong or a sender problem. HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Grim Reaper Posted July 16, 2003 Author Share Posted July 16, 2003 My thoughts exactly... The water temperature stayed even at below 80 all the time the high oil warning was on,I would expect the water temp to rise as it was trying to soak some of the heat away if the oil was really getting that hot. Will try a probe down the dipstick tube or stick it to the filter housing to see if it mirrors the dash reading or not. Link to comment Share on other sites More sharing options...
Mark Chilton Posted July 16, 2003 Share Posted July 16, 2003 An alternative to a temperature gun and at a cost of little more than a few quid is to buy a decent thermocouple and LCD display. The thermocouple you can bond into one of the recesses in the block. This should give a permanent and believable indication of engine temperature and hopefully the peace of mind that you seek Mark CATCH THE WIND Link to comment Share on other sites More sharing options...
Chris W Posted July 16, 2003 Share Posted July 16, 2003 Grim Re the sender resistances. Were you measuring the sender resistances in isolation? ie: with the connector wire pulled off the top of them? If not you will also be measuring the (fixed) resistance in parallel with the sender inside the gauge. If the senders are only, say, 10% accurate, the resistance results you measured could be misleading as the tolerances in the resistance values means they could easily overlap. ie: just because the resistance of the water sender is lower at a lower temperature it could just be tolerance spread. eg: 605 ohms less 10% = 550 ohms. 523 ohms + 10% = 575 ohms. So it doesn't necessarily mean there is a sender problem. However, I have no idea in reality if the senders are significantly more accurate than 10%? Anyone know? Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Grim Reaper Posted July 17, 2003 Author Share Posted July 17, 2003 Took readings at sender and at wiring block connectors,only an ohm or less in difference. Swapped oil and water wires over and went to local area meeting in York last night. Water (now reading oil temp) gauge now up at 125 deg C and varying wildly at times (from 76 to 126) oil (now reading water temp) stayed down at 65. The difference between just swapping gauges is a little strange,as the water temp is now 10 degrees lower than with its own gauge. But since I went out and bought an infra red thermometer last night and took a reading off the oil filter of 80 degrees I think this confirms the sender is playing up. I'll be speaking to Stack later today.I'm not happy that it only lasted a thousand miles before breaking. Link to comment Share on other sites More sharing options...
Chris W Posted July 17, 2003 Share Posted July 17, 2003 Grim From what you say, re the difference in indicated water temperature after swap over, I would infer the senders are not actually identical (or have a very wide tolerance). It certainly appears, on the evidence, that the oil sender is faulty. I had my water temp sender die on me within 3 weeks of having the car from new. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
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