Boiling up

[aerosam]

Hi guys, I ran my engine up to temperature today, to ensure the temp guage is working and to recharge the battery.

After 20 mins of idling, the expansion tank boiled up and water flowed from the overflow. However the radiator remained cold, along with the bottom hose. The top hose feels empty.

I'm suspecting a stuck thermostat? Any other ideas?

[K4KEV]

yep... would say stuck stat as well... take it out and chuck it in some boiling water cool it under tap ....watch it to see if it opens(in hot water) and closes (cold tap) repeat several times to 'break' it back in, then check opening temp by gradually heating in water.
if fubar'd buy a new one ....they are only coppers:D
oh forgot to ask....your water pump is working isn' it ?

[aerosam]

Haven't checked water pump yet, but will do.

I'll definitely be pulling the stat out and checking to see if it's working or not. Just priced a new one, £52 inc VAT from my local motor factor! Was quite a funny phone call actually, they needed a registration number to identify the exact model of BMW I had so i gave them the one of the donor. The line went very quiet for a while so i asked if I'd got the number right, and explained i wasn't sure as I'd broken the car a couple of years ago.

With a huge sigh of relief, the lady on the other end says "I'm so glad you told me that, I didn't have the heart to tell you your car had been scrapped!"

:D

[K4KEV]

before you know it ....they will know the last time you farted or squeezed a zit:eek:
52 notes.....never thought I'd here me say I'm off to the local scrappy for a stat

[twinturbo]

before you know it ....they will know the last time you farted or squeezed a zit:eek:
52 notes.....never thought I'd here me say I'm off to the local scrappy for a stat

You wana see the price of one for a 24V Ford Scorpio.

TT

[aerosam]

You wana see the price of one for a 24V Ford Scorpio.

TT

Go on TT I do love having a good Harrrumph, how much?

[aerosam]

If turns out not to be the stat you may have an air lock.

Hmm, might try that first actually. As I'm guessing it might be easier.

I'll take the rad top hose off and make sure it's filled with water then try again.

[twinturbo]

Go on TT I do love having a good Harrrumph, how much?


Think they were £85 last time I looked! and a water pump was about £140.

Annoying thing is that a Granada 24V ( which is almost identical engine wise ) would use a £7 stat and £20 pump.

Thankfully I no longer have a Scorpio 24V engine.



I too would suspect the stat on your engine or the pump. Did 2 stats and a pump on friends cars last year Due to rapid overheating.

TT

[aerosam]

Wow, that be one 'spensive stat.

I'm afraid to say I'm not having much success with this. This morning I disconnected the rad top hose, which was empty, and filled it before quickly reconnecting it. Ran the engine, and after 10-15 mins the expansion bottle was overflowing again. This time I'm sure there was no air in the rad or it's hoses, until it started boiling, when the bubbles found their way into the top hose.

Ok so what's the next step?

I'm thinking disconnect the top hose again, refill and start up for a few seconds with it disconnected to check the pump is working. If it is, remove the thermostat and check it's operation.

What do you guys reckon to running without the stat at all? The rad is only half the size of the donor's, and as it's only going to be used on track it's going to be generating a lot of heat. The extra cooling might be benefecial.

[K4KEV]

You won't get a "flow" unless the stat is open or removed....I would defo check the stat because your symptoms are classic "stuck stat"

[davidimurray]

If I was you I would start by removing the stat. This should make the engine warm up a lot slower (the only reason for the stat is accelerated warm up). While you are warming the car up take it easy and don't give it lots of revs for long periods.

Is your header tank at the highest point of the system? If so I would start the car with the header tank cap removed. As the engine is running, work your way all the hoses on the engine, giving each one a good hard squeeze in turn and checking for any bubbles in the expansion tank and keeping it topped up. You should be able to see some water movement in the tank depending on how you have configured it. You should be able to leave the car idling without it boiling over without the cap on.

Putting the cap on - if it is a 14psi one the the boiling temp of the water will be raised to 119C.

I wouldn't run the car without the stat on the road - as the last thing you want to do is overcool it during the early stages of warming up. If you do decide to remove the stat, put a metal disc with a hole in place of the stat as this will provide with you some flow resistance in the system.

[aerosam]

Hi David,

yeah the header tank is a few inches higher than the engine. I'll have a look at the stat tomorrow afternoon now. I need to get it out of the garage first cos i nearly flooded it the other day fiddling with the radiator hoses!

[alga]

Great advice there, davidmurray, I'm sure it will be helpful to me as well when it comes to filling the cooling system.

I would not consider a "no thermostat" option so risky. I had a stat stuck open on my daily Nissan Primera W10 for several years back in the day. Imagine my joy when having replaced the stat the heater started blowing heat after just 2 km instead of 10! No apparent damage to the engine though.

[aerosam]

OK, earlier I removed the stat. Put it in a pan of boiling water, and it opened about 2mm, but only after a few minutes at a rolling boil.

I take that to mean it's had it, as according to BMW it should open at 85 degrees.

So anyways I cut the centre out of it (the outer ring supported the rubber seal) and refitted it. Refilled the water and ran it. After manipulating the rad hoses to make sure there were no airlocks, the rad got nice and hot, and no more boiling up.

So well done guys - stuck stat it was! Now I just have to find a replacement at a decent price.

[davidimurray]

Aerosam - glad you got it sorted - now you just need to save the pennies for a new one:p

Alga - having a stat in there that is jammed in is fine - remvoing it totally is more of an issue. The stat acts as a restriction in the coolant flowpath and as a result helps to balance the flow to different areas of the block. If you remove the stat then you give the water an 'easy' path through the engine that can result in the engine overheating becuase you don't pick up as much heat.

I had this problem with a engine on the dyno that would constantly overheat no matter how many extra water pumps we added :rolleyes: In the end we realised that the thermostat had been removed and the water was just going around the system picking up very little heat - popped a thermostat back in and it cured all the problems. :D

[baz-r]

Aerosam - glad you got it sorted - now you just need to save the pennies for a new one:p

Alga - having a stat in there that is jammed in is fine - remvoing it totally is more of an issue. The stat acts as a restriction in the coolant flowpath and as a result helps to balance the flow to different areas of the block. If you remove the stat then you give the water an 'easy' path through the engine that can result in the engine overheating becuase you don't pick up as much heat.

I had this problem with a engine on the dyno that would constantly overheat no matter how many extra water pumps we added :rolleyes: In the end we realised that the thermostat had been removed and the water was just going around the system picking up very little heat - popped a thermostat back in and it cured all the problems. :D

it effects the ballance of flow around all the cyl liners
minis used to boil 3&4 and cool 1&2 with the stat pulled out st did a flow restricter ring to replace the stat to ballance the flow
its the same reason why you dont change the size of the coolent holes in a head gasket (and yes i have seen it done :rolleyes: try it and you will find out )

[aerosam]

Progress on this at last - but backwards :mad:

fitted a new stat and it boiled up as before.

replaced the water pump, but when i tried to refill the system from the expansion tank, it simply wouldn't flow into the engine, until i loosened the top hose at the pump end. It then flowed in niceley, i carried on filling till there were no more air bubbles coming from the loose hose then tightened it and manipulated the hoses till there were no bubbles appearing in the expansion bottle.

Ran it up, and guess what, IT EFFING BOILED UP AGAIN!!!!!:mad: :mad: :mad:

I've put a bunch of pictures of it on my blog, please have a look and tell me if you can see something obvious I've done wrong. Really, really fed up with it today.

[minicountryman1961]

Progress on this at last - but backwards :mad:

fitted a new stat and it boiled up as before............................................ .................................................. .................................................. ...............

Remember when you stuffed those paper towels in the lower radiator hose to stop the dripping, did you take them out?

The more I look at your photos, I think you motor is so freaking big it fills the engine compartment and the air can't go through the radiator cause it has nowhere to go.

[aerosam]

Remember when you stuffed those paper towels in the lower radiator hose to stop the dripping, did you take them out?

The more I look at your photos, I think you motor is so freaking big it fills the engine compartment and the air can't go through the radiator cause it has nowhere to go.

Yeah there's no blockages. It is a massive motor dimensionally, the 90 degree vee makes it very wide. The photo's don't show it very well, but there is about 10" clearance bewteen the rad and the engine, and there is no bodywork within the wishbone mounts, providing large holes for the hot air to exit.

[js1uk]

Your header tank looks lower than the engine, The tank has to be slightly higher other wise the tank becomes just like abit of pipework. No expansion. Think of it like a central heating system.
What temp is your fan starting to come on????

[gaz05]

I'm trying to figure out your system. I take it the water is pushed through the heads/block by the water pump to the water rail at the back and then down the pipe in the centre back to the rad. I see the pipe is connected to the pump but I assume this is straight through the pump body to the rad.

Correct me please if I'm being thick but I notice on my tintops (both Zetecs) that the hose coming off the thermostat goes to the top hose on the rad and the pump is fed from the bottom hose. Yours appears to be the other way round.

[aerosam]

Your header tank looks lower than the engine, The tank has to be slightly higher other wise the tank becomes just like abit of pipework. No expansion. Think of it like a central heating system.
What temp is your fan starting to come on????

I've been wondering about the tank, the water level is higher than the top of the heads, albeit marginally. I was wondering if raising it some more would give a head of water above the engine which may help?

The fan isn't coming on as I'm not getting any waterflow through the rad as the (NEW) stat is apparently remaining closed.

[aerosam]

I'm trying to figure out your system. I take it the water is pushed through the heads/block by the water pump to the water rail at the back and then down the pipe in the centre back to the rad. I see the pipe is connected to the pump but I assume this is straight through the pump body to the rad.

Correct me please if I'm being thick but I notice on my tintops (both Zetecs) that the hose coming off the thermostat goes to the top hose on the rad and the pump is fed from the bottom hose. Yours appears to be the other way round.

the pump draws water from the block, and pushes it through 2 external pipes in the vee between the heads to the rear water rail where it flows back into the rear of the heads and round again. The rail also has 2 ports for the donor's heater matrix. The return from the matrix was a Y-pipe witht he expansion bottle on one end, I have attached the expansion bottle directly to this port and blanked the other.

At the front, the pipes from the pump are arranged as per the donor, with the thermostat side going to the bottom of the rad.

[flyerncle]

Check that you have flow returning to header tank otherwise you will have curculaition problems and it will boil.

The Ginetta I have stripped to make a decent car from (Roadster)has a feed to bottom hose from lowest part of header and returns to top of header from top hose.

[aerosam]

Check that you have flow returning to header tank otherwise you will have curculaition problems and it will boil.



What do you mean? My header tank has only one pipe, rather than an inlet and outlet.

[flyerncle]

Usually a cooling system feeds water to the bottom hose from the base of the tank and returns through a pipe in the top hose to the header tank that is again usually seperate to the rad.

Beemers have a vent in the rad that must be bled otherwise you get problems with airlocks and overheating.

I have not checked the zetec from the Ginetta donor but suspect it has no stat in the back of the head but it used to run at about 70/75 deg at race speed and no more.

In my years as a mechanic I've done more than my fair share of Rover head gaskets and changed the stat and put two small holes in them to allow the water to flow easier and stop airlocks everytime I did one,this may help.

[flyerncle]

I looked at your pics,if that hose at the rear of the header is meant to be conected to a water rail somewhere that is your problem as you have no flow return.
Alternatively get a VW/Audi tank and fit a tee in the top hose somwhere and feed it to the top of the tank,use the lower to feed as normal in you blog pics.

[aerosam]

here's a few diagrams from the donor, provided from the bmw parts catalogue, hopefully this will help.

overview showing pump, rad and pipes. What isn't shown are the 2 aluminium pipes which run from the back of the pump to the rear water rail. These are shown in the second drawing, marked 4 and 6.

http://2.bp.blogspot.com/-0tIAQdPcLgg/TaQVD5mA63I/AAAAAAAAAU4/RH_JdhHDLnM/s1600/bmwpipes.bmp

detail of the rear water rail. the port near bolt marked 3, is the one I have blocked up. The expansion tank is connected to the port marked 1.

http://3.bp.blogspot.com/-_vRJsxrrwW8/TaQT8jN2vaI/AAAAAAAAAUo/ZKi4OWBy5hU/s1600/bmwpipes%2B2.bmp

and the original setup of the expansion/header tank.

http://4.bp.blogspot.com/-sJat2WQq5lk/TaQT8Sf8hYI/AAAAAAAAAUg/hcwL3768LJ4/s1600/bmwpipes%2B3.bmp

[aerosam]

Beemers have a vent in the rad that must be bled otherwise you get problems with airlocks and overheating.

In my years as a mechanic I've done more than my fair share of Rover head gaskets and changed the stat and put two small holes in them to allow the water to flow easier and stop airlocks everytime I did one,this may help.

the rad is lower than the pump, i don't seem to have any air in it. unfortuatelt the rad is of unknown origin, i bought it at stoneleight last year, as it was the exact size i needed and it was only a tenner. it doesn't have a bleed screw.

the stat has a small steel ball fitted loosely in a hole at the top of the stat, i'm guessing it's air bleed device, but it wouldn't be difficult to pull the stat out and drill it, might try that, thanks.

[AshG]

i think this is the same problem i had with my Saab engine. i blocked off the heater circuit and it kept doing the same thing. on some engines the heater circuit has to have a constant flow or it overheats before the stat opens. unblock 3 and either take it to the top of the header tank or splice it into the top rad hose.

a good tell tell sign of the system flowing properly is that you should see water returning to the header tank through the top pipe. if that is not happening then there is something wrong.

[Enoch]

Here's a really daft idea - have you changed the routing of the water pump drive belt? If so is the pump turning the right way? If it was forcing water back against the wrong side of the stat then it would overheat with the stat in but would probably be ok with the stat out. By the same token - is the stat in the right way round?
Might sound daft but thought it worth asking.
Enoch.

[flyerncle]

Ash has hit it on the head as I posted previously,the small pipes in the drawing are returns to the top of the tank and if you have no water in the system returning it wont pump and what ever is close to the cylinders and top of the head will boil as it cant circulate.

It may be a different system to what I have seen previously on BM's so the bleeder may not be there.

[aerosam]

Here's a really daft idea - have you changed the routing of the water pump drive belt? If so is the pump turning the right way? If it was forcing water back against the wrong side of the stat then it would overheat with the stat in but would probably be ok with the stat out. By the same token - is the stat in the right way round?
Might sound daft but thought it worth asking.
Enoch.

No not daft at all, I have indeed re-routed the belt to remove the power steering pump, but it is still turning the same way.

Thankfully the stat is idiot-proof, only fits in the right way round, and only with the bleed valve at the top.

[aerosam]

Ash has hit it on the head as I posted previously,the small pipes in the drawing are returns to the top of the tank and if you have no water in the system returning it wont pump and what ever is close to the cylinders and top of the head will boil as it cant circulate.

It may be a different system to what I have seen previously on BM's so the bleeder may not be there.

Ahhh, now I understand! Ok so what i need to do is unplug the 1 heater port and route it to the other, then use a T-piece to tap off to the header tank? is that right? That should restore flow round what was the heater circuit. I can't take it to the top of the tank as there's nowhere for it to go.

pipe 11 is definitely an overflow as it simply flowed down to the underside of the car on the donor, pipe 6 was connected to a small port next to the rad top hose on the donor - but my new rad has no such port :( I assumed that they were both overflows as the header tank cap has 2 o rings with a 1/4" gap between each which allows water to flow to either of the 2 pipes. It's not shown on the drawing at all.

I can't remember if the donor had a bleeder, and the drawing doesn't show that much detail :confused:

[aerosam]

Ok, had a guts full fo this thing now. :mad:

replumbed the water rail to allow the heater circuit to flow, which it did nicely. Got all the air out, ran it and guess what, the f***ing thing boiled up -AGAIN!

Just pulled out the brand new stat and put it in a pan of boiling water, after a minute or so at a rolling boil - it opened about 2mm - surely this isn't enough? I'm gonna drill a couple of holes in it now and put it back in. it cost me £50 but f*** it i'm all out of other options.

one pissed off builder.

[CTWV50]

Could it be a headgasket? You can get a sniffer test called a block tester, and it sniffs for carbon monoxide in the header tank steam. Search ebay they are about 20-30 quid.

Edit: oh a bit more expensive!

http://cgi.ebay.co.uk/UNIVERSAL-CYLINDER-HEAD-COMBUSTION-LEAK-BLOCK-TESTER-/260768592469?pt=UK_Hand_Tools_Equipment&hash=item3cb704f255#ht_1134wt_907

[flyerncle]

Ask friendly mot tester to sample header tank for HC as there should not be unburnt fuel in it,if there is the head gasket is donald ducked.

[aerosam]

Ok, calmed down a little now - drilled 2x 4mm holes in it and refitted the stat, refilled and bled the system, started it up. Water flowed through the rad and it got hot within a couple of mins. Water temp rose to about 65 degrees and seemed to stay there, after 5 mins i shut it off.

No boiling in the header tank but definite bubbling noises coming from somewhere for a few seconds. ???

removed the sump plug to drain the oil while it's hot - will go back to it tomorrow now.

[flyerncle]

Is the total rad hot from top to bottom after the stat opens,I still think the problem is flow to header related,one way or the other it needs to go back to the highest point.

Bin the B EM one and start again with a ford or vag one as they have top returns and feed from the bottom of the tank.

Water fed to bottom hose and tee into top hose to bleed return to top of tank.

[aerosam]

Is the total rad hot from top to bottom after the stat opens,I still think the problem is flow to header related,one way or the other it needs to go back to the highest point.

Bin the B EM one and start again with a ford or vag one as they have top returns and feed from the bottom of the tank.

Water fed to bottom hose and tee into top hose to bleed return to top of tank.

Yeah the rad is hot throughout seems to be ok now :)

Here's how it looks now, sorry for the huge pic.

http://2.bp.blogspot.com/-kgBCo4e7ns0/Taf6if3zZlI/AAAAAAAAAVA/g8y2KJxXRPM/s1600/Image0211.jpg

I've got it plumbed like this as it's the closest I can get it to how the donor was set up. I'm not going to be able to work on it again now till Sunday but then i'll give it another long run and see how the temperature control works when the cooling fan kicks in. (so far it hasn't as the switch is in the rad bottom hose)

I'll pop to a scrappie on Saturday and see what I can lay my hands on as a new header tank with a flow through.

I don't quite follow "Water fed to bottom hose and tee into top hose to bleed return to top of tank" can you expand a little?

Thanks for all you help.

[flyerncle]

Been looking at every vehicle I have repaired over the last week (Sad ) and 99% feed water to the bottom hose from the bottom of the header tank and the top hose goes from rad to engine,some have bleed from top of rad to top of tank and others had feed from top hose to top of tank.

Logically thinking if you only feed water to one hose only where is it going to go,to achieve cooling you need to move the water through the rad to get heat transfer and therefore cooling, still convinced the two pipes coming from the filler neck in the picture are the answer to your problem and tying in those two heater pipes to the two pipes at the neck will give you flow.

Pm me if you want a phone number to discuss it.