428 FE thermostat

[Vince Caldicott]

I,m having problems losing water only after parking the car, it seems that once the engine switches off the top up tank filler cap dispenses about half a pint of water. I thought that I would check the thermostat was working correctly, on removing the header tank and thermostat housing I have found that there isn't a thermostat fitted, however there is a brass plate in the tube to the header tank with an offset hole of approx 17mm drilled through it. It looks like a flow restrictor/baffle plate. Is this A replacement for a thermostat ? Any advice would be appreciated.

[rsk289]

Hi Vince,
   I'm not familiar with your particular application (which car is this?), but unless your brass plate is factory-fitted, restrictor plates are not a great idea.  A correctly-rated themostat will help to allow the engine to warm up at the desired rate and will go some way towards maintaining the correct running temperature, assuming the cooling system is in good shape.  Original Cobra systems can be tricky to fill, and for a 289 I find this works best:  remove air bleed screw in the top hose, fill system as far as possible via header tank.  When this is full, disconnect O/S heater hose at bulkhead and back-fill towards engine using a funnel (ensure heater tap at front of block is open).  Eventually coolant will come out of the bleed screw - close everything up and run up to thermostat temp, then switch off, allow to cool and top up at tank if necessary.
   It's a good idea to drill a small hole in the top of the thermostat to allow air bleed, if it doesn't already have one.
   Has it always done this, or is it a new problem?

[Vince Caldicott]

Hi Roger, thank you for your helpful reply. I've only had the car since March and it has had the problem since I bought it.I have Trevor Legates 427 sc continuation car COX5012 which has a 428 FE installed. I'd doesn't have any heater pipe work and unfortunately at the top front of the engine where the water connects to the header tank the metal isn't rebated to take the thermostat unless I use a very thick gasket. I'm not sure if that would be a good long term solution. However, since I posted the question I have managed to get hold of a replacement side oiler which is being installed in August. I am due to go to the Silverstone Classic at the end of the month so I Have refitted the header tank without the thermostat, bled the system as best as I could  and hope it will get me there and back (approx 300 miles). With the engine ticking over and the filler cap removed everything seems ok, however, if I Rev the engine the water all bubbles up and spills over. Do you thing this is the water pump just pushing it over or could it possibly be a head gasket? The oil looks clean. Warm regards. Vince

[rsk289]

I think it unlikely that it is a head gasket problem.  Does it drive OK?  Firing on all 8?  Can you do a compression test?  Any sign of coolant in the engine oil?  Any sign of oil in the coolant?  Is it running particularly hot?
   With the cap off, I would expect the coolant to spill over due to the water pump action after the thermostat has opened.  If you don't have a thermostat, I guess it would do this pretty much straight away, especially as you don't seem to have an easy way to bleed the system.
   It sounds like your best plan is to do as you say, make the trip to Silverstone with a 'new' motor planned for the near future.  I really can't offer specialist advice on the FE motors as I only know small-block Windsors - I seem to remember the 427 has the thermostat housing built into the header tank, but may be wrong on that.  Either way, if it drives OK and doesn't show signs of serious overheating, you should be OK.  Carry some water to top up, and if it starts to get very hot switch off in the S'stone queues!
   I'll be with the 289 Register with my 289, which regularly runs at between 90-105°C, especially in these temperatures.  I'm running Evans so it's not going to boil and has not shown any signs of distress thus far, so fingers crossed.
   What pressure rating cap are you using?  Coolant expands when hot and you are probably getting overflow at switch-off due to the spike in temperature caused by the water pump ceasing to turn.  I have a catch tank for the coolant overflow, which sucks back into the system as it cools down.
   Are you filling it right up each time?  It may be that the system wants to run with the quantity of coolant left after it's overflowed.  You may need to just leave it as it is, but carry water just in case.  I'd still like to see a thermostat in there somehow, though - maybe in the side-oiler!

[Vince Caldicott]

It starts and runs well, have replaced the spark plugs and inspected the old ones, no sign of scaling on any of the old plugs. Oil is clean and no sign of oil in the water. I top it up until the header tank is half full. I think it could be as you say a spike in temperature after switching off. I will take your advice and take 10 litres of water for the journey to Silverstone. I am going to Silverstone on the Saturday, if you are there I will look you up. Thanks for all your help and advice, it's very much appreciated. Vince

[Jam2]

If you are getting a certain amount of foaming of the coolant, it might be worth trying 'water wetter'.
   http://www.redlineoil.com/product.aspx?pid=74&pcid=10
   It worked for me, although in a completely different type of engine, stopping the foaming and consequent water loss.

[Vince Caldicott]

Thank you. That sounds like it might help. Is it available in the uk?

[Vince Caldicott]

Just ordered some on e bay. Thanks for your advice. I will let you know if it helps.
   Vince

[Flyinghorse]

Have you looked at the pressure rating of the cap on the headertank--perhaps it needs uprating to deal with the pressure spike that are causing it to dump fluid when stopped. (ie fixed volume,temp rises,so pressure increases,cap pressure rating exceeded so it dumps water.)
   
   If you look at the water wetter charts they suggest running 100% water & wetter for best results/maximum cooling.
   
   Do your fans run on after stopping? Perhaps they need wired in so that they do.
   
   Inline (ie in hose) Thermostats are available (i had one in my Bristol 400 for a while).Some MG's have them. Kit car parts supplier also make inline housings that hold them.
   
   Graham

[rsk289]

It's certainly worth checking the cap for seal and for pressure rating.  If you're going to run neat water you will need to keep a very close eye on corrosion.
   I'd be wary of having electric fans operational on an 'always live' circuit - I've had to deal with far too many flat batteries because of that arrangement!  Fans take a lot of juice out of the battery.  That setup makes much more sense if you are also running an electric water pump (which will use even more juice).  If not you are only blowing air over the same bit of stationary water in the rad, the cooled water is not circulating.  There will, however, be some effect of air blowing over the block, but I doubt that would stop your water loss at switch off.  I'm guessing the water loss is pretty much as soon as you switch off.
   I'd fit an expansion tank.

[Vince Caldicott]

Thank you both for your input. I,ve topped up the water with the wetter wetter product.  I'm going to the Silverstone Classic event tomorrow with the car so Today I,ve driven from Brighton to a friends house in Long Crendon to break the journey, 100 miles of mostly motorway driving. Solid nose to tail traffic from Gatwick to M40 which took  nearly 2 hours to cover 35 miles. Kept an eye on the temperature gauge, the big electric fan kicked in at about 80 degrees, did not need to use the twin electric fans to keep the temperature down. Total journey time was just over 3 hours. Checked fluid levels half an hour after arrival and pleased to report no fluid loss, so it seems that the wetter wetter products has solved the problem. Today has been a real first test for this car which I don't believe has ever been driven in the rain or in very heavy traffic, today we had plenty of both.

[Vince Caldicott]

P.S One other thing, I replaced the expansion filler cap with one rated at 15lb.