Discussion
Hi,
Only bought my '94 Chimaera 4 a month ago but a week later, the lower outlet, short U rad hose sprung a pinhole leak and I replaced it with a BMW part cut to size. Now I know this sounds odd, but since I bled the system, she is running at a much cooler temp and the oil pressure rarely goes above 30.
An example was this morning- thought I'd treat her to a blast up the M1 to cough out any deposits from crawling to work each day. Took it easy for first 20 miles & temp read virtually zero. Only when I hit the inevitable jam did the temp rise to around 50 & oil showed about 30. On the way back, took her to a steady 125mph but the gauges didn't increase. Sorry this a bit long winded but is the car now running 'too cool' & is oil pressure affected by that? I know that the gauges are (fairly) accurate cos of miles done before the hose burst. Any advice would be appreciated.
As a ps, Ted- this is such a good site. Unknown to you guys & girls, you were instrumental in my car choice. And Scruff- don't ask- long time ago I was a greenkeeper. I think it was Samual Johnson who said 'golf- a good walk wasted'
Only bought my '94 Chimaera 4 a month ago but a week later, the lower outlet, short U rad hose sprung a pinhole leak and I replaced it with a BMW part cut to size. Now I know this sounds odd, but since I bled the system, she is running at a much cooler temp and the oil pressure rarely goes above 30.
An example was this morning- thought I'd treat her to a blast up the M1 to cough out any deposits from crawling to work each day. Took it easy for first 20 miles & temp read virtually zero. Only when I hit the inevitable jam did the temp rise to around 50 & oil showed about 30. On the way back, took her to a steady 125mph but the gauges didn't increase. Sorry this a bit long winded but is the car now running 'too cool' & is oil pressure affected by that? I know that the gauges are (fairly) accurate cos of miles done before the hose burst. Any advice would be appreciated.
As a ps, Ted- this is such a good site. Unknown to you guys & girls, you were instrumental in my car choice. And Scruff- don't ask- long time ago I was a greenkeeper. I think it was Samual Johnson who said 'golf- a good walk wasted'
Can only offer you (un)educated guess work on this as i haven't had this kind of problem on any previous cars myself, however here goes 
.
Cold oil normally gives a slightly higher pressure than hot (well it does on mine!), a leak on a radiator hose is imho unlikely to lead directly to the below problems, I do believe in coincidence though.
Over cool running can sometimes be attributed to the thermostat being stuck open.
However all that said I would be inclined to think that as you have two instruments giving 'wrong' readings I would look in that area for lose wires, poor earths etc (electrics do seem to be one of the weaker point of Tivs :understatementsmileypleaseted
).
To save time ou could get the gauges verified by getting the oil pressure and engine temperature measured at a garage before pulling your hair out and changing bits that don't need changing.
Obviously all IMHO, I hope this helps/hinders
.
Harry
. Cold oil normally gives a slightly higher pressure than hot (well it does on mine!), a leak on a radiator hose is imho unlikely to lead directly to the below problems, I do believe in coincidence though.
Over cool running can sometimes be attributed to the thermostat being stuck open.
However all that said I would be inclined to think that as you have two instruments giving 'wrong' readings I would look in that area for lose wires, poor earths etc (electrics do seem to be one of the weaker point of Tivs :understatementsmileypleaseted
). To save time ou could get the gauges verified by getting the oil pressure and engine temperature measured at a garage before pulling your hair out and changing bits that don't need changing.
Obviously all IMHO, I hope this helps/hinders
. Harry
Thanks Harry,
I felt I was getting fairly correct readings from gauges this morning but I seem to remember a thread on here that suggested engine damage could occur running a Chim over cooled- but is that realistic? I would've thought the cooler the better- or is that naive? Got to bear in mind that we're into winter air temps now- as a by the way, the upholstery in the driver's seat appears to have gone thru the floor (previous owner(s) not strangers to pies!) How easy is it to swap seats thus making the passenger feel that their ass is sinking into quicksand & not the drivers?
I felt I was getting fairly correct readings from gauges this morning but I seem to remember a thread on here that suggested engine damage could occur running a Chim over cooled- but is that realistic? I would've thought the cooler the better- or is that naive? Got to bear in mind that we're into winter air temps now- as a by the way, the upholstery in the driver's seat appears to have gone thru the floor (previous owner(s) not strangers to pies!) How easy is it to swap seats thus making the passenger feel that their ass is sinking into quicksand & not the drivers?
Kenny,
I don't know what the weather was like up your way yesterday, but down here it was very cold and frosty. I only say this because when I had my Chimaera, in the winter when I drove up the M3 to London (about 30-35 miles) the temperature never moved off the bottom of the guage. Which I put down to all that cold air running over the engine. Once in London, and the speeds were a lot lower, the temperature would gradually creep up to normal.
Neil.
>> Edited by neilus on Sunday 20th October 09:38
I don't know what the weather was like up your way yesterday, but down here it was very cold and frosty. I only say this because when I had my Chimaera, in the winter when I drove up the M3 to London (about 30-35 miles) the temperature never moved off the bottom of the guage. Which I put down to all that cold air running over the engine. Once in London, and the speeds were a lot lower, the temperature would gradually creep up to normal.
Neil.
>> Edited by neilus on Sunday 20th October 09:38
That does sound wrong I have to say. The car needs to be in the 70-90 degree range for various reasons. Below 70 and the oil does not get hot enough and starts to cause excessive wear over time and especially if revved hard over 2500-3000 revs or doing 125 down the motorway.
I would check the guage as they can go wrong but I suspect that you have a jammed open or no thermostat. Until this gets fixed keep the revs down otherwise you could end up with a bill for a new cam...
It could be air flow in which case block off some of the rad intake. It is important to get these car working at temp.
Steve
www.tvrbooks.co.uk
>> Edited by shpub on Sunday 20th October 09:42
I would check the guage as they can go wrong but I suspect that you have a jammed open or no thermostat. Until this gets fixed keep the revs down otherwise you could end up with a bill for a new cam...
It could be air flow in which case block off some of the rad intake. It is important to get these car working at temp.
Steve
www.tvrbooks.co.uk
>> Edited by shpub on Sunday 20th October 09:42
My neighbour, who designs cooling systems for Jag for a living, reckons its is not possible to overcool if a thermostat is fitted and working. The thermostat will regulate engine temp as it is designed to do. Once the thermostat is fully open radiator size and efficiency determine how quickly coolant temp will be reduced, and the bigger the temp drop across the radiator the better.
If your heater is blowing out hot air the thermostat should be working properly, Since i flushed the cooling system out and added waterwetter the temperature in my car has dropped on the motorway down to 65 with plenty of hot air from the heaters and around town stuck in traffic 80 compared with a stuck on 88 without the flush and waterwetter.
neilus said: Kenny,
I don't know what the weather was like up your way yesterday, but down here it was very cold and frosty. I only say this because when I had my Chimaera, in the winter when I drove up the M3 to London (about 30-35 miles) the temperature never moved off the bottom of the guage. Which I put down to all that cold air running over the engine. Once in London, and the speeds were a lot lower, the temperature would gradually creep up to normal.
Neil.
>> Edited by neilus on Sunday 20th October 09:38
On mine (V8S), there's enough air blast cooling to hold it at fiftyish degrees while cruising in freezing weather. (This is about a third of the way up the gauge on mine.) By blocking off half the front grill I can reduce the air blast cooling enough to bring it up to about seventy degrees, which is where the stat opens. However, if your stat is missing or faulty you'll see a similar but much more dramatic effects because you'll get full rad cooling as well as the air blast cooling on the engine. Possibly this is what you're seeing. You can check the operation of the stat very crudely by starting the engine from cold and seeing how quickly the top hose feels warm to the touch. If it's almost immediate, that suggests a problem with the stat.
Cheers,
Peter Humphries (and a green V8S)
VictorMeldrew said: My neighbour, who designs cooling systems for Jag for a living, reckons its is not possible to overcool if a thermostat is fitted and working. The thermostat will regulate engine temp as it is designed to do. Once the thermostat is fully open radiator size and efficiency determine how quickly coolant temp will be reduced, and the bigger the temp drop across the radiator the better.
Not quite the case as air flow over the engine can have a big effect and some engines (like mine) appear to have a bleed where some water flows through the rad anyway. With big cold air flow, the engine never generates enough heat to get the water upto stat opening temp and so the engine runs cold...
Being careful not to fall into the previous discussion... it does appear that the stat is modded or a modified thermostat housing has or may have been used to change the thermal equilibrium characteristics. At a guess it is the drill holes in the stat mod but I have found references to modified stat housings that allow bleed through.
Certainly seen the modified stat housing on some 1990s 400SE's so I think they are out there. This was an external plumbing job but there are hosuings that are modified internally. As to when and where the mods have been made is really unclear but I don't think my car is the only one. I suspect it may have been a if this car is borderline, we'll try this.
Seems to work fine on my car and it does explain all the set up problems I had originally with the two speed fan.
it does appear that the stat is modded or a modified thermostat housing has or may have been used to change the thermal equilibrium characteristics. At a guess it is the drill holes in the stat mod but I have found references to modified stat housings that allow bleed through. Certainly seen the modified stat housing on some 1990s 400SE's so I think they are out there. This was an external plumbing job but there are hosuings that are modified internally. As to when and where the mods have been made is really unclear but I don't think my car is the only one. I suspect it may have been a if this car is borderline, we'll try this.
Seems to work fine on my car and it does explain all the set up problems I had originally with the two speed fan.
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