[seynhaeve]

Hello all,

I'm trying to fix my cooling system for a while know, but nothing seems to work.

Whenever the engine hits optimal temprature, the coolant in the cooling reservoir begins to boil and the fan doesn't want to turn on any more.

There are no signs of oil and coolant mixing, so no "mayonaise" in the oil reservoir.

I tried changing the thermostat / thermoswitch but nothing seems to work.

Does anybody has an idea, or experience with this problem?

Thank you in advance.

Nicolas.

 

[CharlieL]

Have you tried shorting out the thermoswitch, does the fan come on? That would tell you if the rest of the fan circuit was working.

Have you bled the radiator?

Also, have you checked the radiator hoses as the car warms up? If you had a blocked or collapsed hose, one or more of the radiator hoses might feel cool. That could that keep the water from getting to the radiator, which would explain why the thermoswitch was not turning on.

 

[fusi]

Have you checked the radiator cap as well?

 

[kuni123456]

I would short out the thermo switch and see if the fan turn on. I had the same problem with both of my Milanos, and the overheating was caused by the fan relay located on the left front side of the engine compartment. The relay is the second one with a fuse located on the top. The first relay is for the horns and will not work for the fan. The relay points were burned out and the fan did not turn on. I purchased the relay from either Centerline Alfa or International Auto Parts. I carrying a spare relay just in the trunk.

 

[seynhaeve]

Hello,

Many thanks for the replies.

The radiator has been bled. The cap of the thermostat was indeed broken but replaced last week. The radiator hoses are all on temperature, so no blockage there.

I shorted out the thermoswitch. The fan works as it should. It works great till the oil temprature gets to 80°, after that point it refuses to turn on again.

The radiator stays at the proper temprature aswell.

Next week I'll pull the radiator out and check for any blockage in the circuit. Till that time, I'm greatfull for any other suggestions.

Greetings,
Nicolas.

 

[IRONBLOCK]

Hi Nicolas,

I have been struggling with a similar issue since April. See:http://www.alfabb.com/bb/forums/alfa-romeo-montreal/405681-such-cool-car.html

So far, the fan switch has been replaced, the coolant has been replaced and coolant system bled; new thermostat and "thermostat cap" (well it's not on the radiator) and all new Romablok hose clamps. I have a jumper connecting the two fan switch wires so that anytime the key is 'on' the fan is running. One difference I noticed between your situation and mine is that my temperature gauge reads increasingly higher, until I pull over and let the engine cool down.

For what it is worth, I tested the old fan switch and thermostat, in a pot of hot water on the stove with a thermometer, after replacing them and both tested good! The engine does run cooler with the fan continuously on but is still prone to get 'too hot'. My friend Tom suggested that I remove the thermostat but I have not tried that yet and believe doing so may be another 'potential cause' of overheating as coolant in the radiator does not have enough time to dispel heat, before going back into the engine.

Larry Dickman built this engine, he offered that there had been some issues with the 'Athena' brand of head gaskets; where the 'fire ring' deteriorates. He suggested I run a compression test on the engine, which I have not done yet but will. See here: http://www.alfabb.com/bb/forums/alfa-romeo-montreal/430777-gasket-requests.html

Another possibility that Bruce Montrealmighty" mentions in "The Essential Companion" (a fantastic resource, if you don't have a copy by the way) is the possibility of leaking hoses or cracks in the head: "As the pressure in the circuit rises, coolant is expelled into the compensating reservoir via the spring-loaded sealing ring of the filler cap above the thermostatic valve. If the cap seal is compromised by wear or corrosion, air instead of coolant may be drawn back into the system when the engine cools. As a result, air and excessive coolant can be expelled through the reservoir the next time the engine is run. Very slight leaks at gaskets or coolant hose clamps can cause the same effect. On the other hand, a continuous stream of bubbles in the coolant while the engine is idling normally indicates leakage of combustion gases due to a cylinder head crack or a defective cylinder head gasket." Cooling: The Alfa Romeo Montreal Website

See also: The Alfa Romeo Montreal Website
I have not studied the engine cooling system enough to understand how combustion gasses can get into the cooling system causing it to overflow; especially without oil being in the coolant or coolant in the oil.

Depending on the results of the compression test, it will be determined whether to re-torque the heads nuts or not. Tom has already graciously loaned me his entire specialty collection of 'rather odd looking' 17 mm closed end wrenches for my torque wrench, should they be necessary.

Mark

 

[SHaszz]

I re-torqued the head nuts (they had another 1/2 turn in them) and it worked. It sealed the head gaskets further down to prevent water loss.

 

[IRONBLOCK]

I re-torqued the head nuts (they had another 1/2 turn in them) and it worked. It sealed the head gaskets further down to prevent water loss.

Had your engine been recently rebuilt or does it have some mileage on it? If so did you remove each head nut to clean and lube prior to re-torquing them? Was the coolant bubbling over in your overflow bottle after a drive?

This morning, the engine (under the 'thermostat cap') was about a quart low on coolant from our last ride when I filled it up. When the engine had cooled down tonight -from our 10 mile drive , again, the coolant was a quart low; the same as it was before our ride. It appears that the engine pushes more coolant out than it can suck back in as it cools. I'll check the hose clamps to the coolant reservoir but suspect too much coolant is getting pushed out of the engine, by compression gasses, for contraction of the coolant (as it cools) to bring the 'engine' coolant level back up to full.
Mark

 

[CharlieL]

I'm puzzled why the radiator will no longer turn on once the oil temp reaches 80 degrees. Can you jumper the thermoswitch and see if the fan then stays on once the oil reaches 80 degrees. That would tell you if there is an electrical issue with the fan circuit, or if there is a reason why the thermoswitch is not seeing the coolant temperature at the radiator.

 

[IRONBLOCK]

I'm puzzled why the radiator (electric fan) will no longer turn on once the oil temp reaches 80 degrees.

The thermostat 'opens' at 85 C and the thermo-switch turns the electric fan on between 90 and 95 C so his coolant is probably not hot enough to turn the fan on. I connected both the wires from the thermo-switch so my fan runs whenever the key is on and I still have coolant bubbling in the overflow bottle and occasionally coming out the top after a long trip.

The fan switch is mid way down the radiator so the coolant level in the radiator would have to be 'half full' or less before the thermo-switch could not 'read' the coolant temperature.

Mark

 

[Montikai]

On my car I have the same problem years ago. Both head´s are cracked. After wellding the heads everything is fine.

Cracked heads are boiling in the reservoir. Sometimes also the head caskets. In bigger garages they can help you with an "Co" tester. Then you knowing it will be gas or it will be "only" boiling water. It is faster and cheeper as change all possible parts.

Kai

 

[Alistair Muir]

Hard water produces calcium and silicate deposits in system. This reduces heat transfer by a significant amount creating some really hot spots that you'll not know from coolant temp and the uneven heat can crack heads.. One way to always have soft water is just use rain water collected in a plastic container saved for when you need it for top ups etc..

The thermostat may have air bubbles streaming over it produced somewhere in engine if it has rough mineral deposits.. Kind of like the tips of a ship's propeller causing cavitation in water flow.... oxygen bubbles can be produced on coolant side of cylinder liners if pitted from corrosion as well. And there's the corroded water pump impeller too can cause this as well..

Not mentioned is gases getting past cylinder liner seals, (on a lower scale - check crankcase ventilation is not blocked adding blowby pressure here).. Maybe a seal rejuvenator additive in your oil can help this one. takes time to do it's magic..

Could explain the appearance of what looks like boiling in reservoir and temp reads lower than boiling..

Never use hard water in your cooling system.

Increasing coolant ratio can help control oxygen bubbles being produced but will lower the good overall heat transfer properties of water in system.. may have to find a happy medium with a bit of testing of coolants. Having an overall hotter running engine without the air bubbles may be safer than cooler with the uncontrolled cavitation hot spots..

You could use a hand held temperature reader and take readings around engine to see if there is anything to be concerned about...

The Evans waterless coolant is supposed to stop oxygen being produced in engines.. but as far as I've read has lower overall heat transfer properties.. It's pure glycol based coolant..

 

[IRONBLOCK]

water pump housing vent

In this listing on eBay there is reportedly a Montreal water pump housing which clearly has a vent up near the top center. It is almost impossible to see the water pump housing 'bleed bolt' while it is on the car.

Papajam made a post some while back and mentioned that there was a bleed nipple on the heater valve of the spider. I've looked on the Montreal but it is very difficult to see the valve behind the center console, let alone a bleed nipple.


Last year when I changed the coolant I used only the thermostat housing 'bleed bolt' to get all the air out and it worked fine. This year, I even used my new "Spill Free" funnel without success. This is a great funnel that I use all the time. I learned about it from 'Eric The Car Guy' on YouTube, watch the video here (just click on the link and scroll down to the yellow funnel and hit play button; no need to sign in or anything): Topic: Trapped Air in Heater Core? Bleed process? (1/1) - EricTheCarGuy - EricTheCarGuy- Stay Dirty!
I thought if this mechanic's 'nasty yellow funnel' looks that bad, I need to get one!

Mark

 

[Alistair Muir]

Eric's got some useful common sense tips. I think he probably makes a good living off them now too...

 

[alfasrule]

You got an air pocket in the system!

 

[IRONBLOCK]

You got an air pocket in the system!

Alfasrule, I sure hope you are right about that! I've been messing around with this issue since April. Would you please provide suggestions to correct this situation? It seems the car has an endless source of bubbles in the coolant.

Mark

 

[IRONBLOCK]

In bigger garages they can help you with an "Co" tester. Then you knowing it will be gas or it will be "only" boiling water.
Kai

Would they check the coolant overflow bottle for the presence of CO emissions? Kai, did you remove the heads yourself or have it done at a shop?

Mark

 

[SHaszz]

Mark.
The engine had done 60,000miles. We lubricated the washers and re-torqued them but at a higher value than the manual (wrong data by Alfa ). It don't remember the figure but at least 10 % higher than what was written in the manual. The compression test won't detect any micro-leakage.
Also I put in a 14lb radiator cap instead of 7lb and I had no coolant loss. It is worth trying.

Steve

 

[Montikai]

Hi Mark,

yes they will do it like you say. A gases measured in Cooling will tell you how much is in it. A little is everytime in it.

The problem I have was only from time to time. Not everytime I drive the car. Some times on long distance all was perfekt. Other time only e few kilometers (14 to my garage) I loose the complete coolant.

I do all maintance by my self and also the engine I have 3 times open. 2 times the mistake was by my self!. (Learner at 8c) Chain tension right side!. I do it like the book (Alfa) sayes. This I know now is the wrong way. Expensiv learning.

The reasen I open first time the motor it was, overflow the water from coolant reservoir. Sorry but I don´t have digital pictures of that. When the heads are remove I don´t see nothing????!!! Also the gasket´s looks not bad???!!!. Than I start a normal overhauling from the enginebay to the heads. After removing all parts out from the heads I give it to a spezialist for checking the heads for cracks etc. 1 week later they call me and they want that I come to them. I have never seen such bad heads from Aluminium ever!. The cracks from the spark plugs on 6 goes deep into the heads to cooling drains. My heads had aluminum corrosion. The italiens don´t use antifreeze. So we had bad Water that was not PH neutral. Also the cylinders was massiv with corrosion, the mix of Alu and iron was realy bad for my heads and some other parts. This company make big big holes into my heads and start wellding from good material. Unbelievably after they finished the work how it was looking.

With new Valves and guide´s, parts from Porsche (valve cups) and Mercedes (Springs) Camshafts with 2ltrs. cam profiles (because on 2 cam´s on 2 camshafts we had bad profiles) At this time 2003 I don´t have any spare parts or any contact to Bruce or to a forum. That´s why I do it all with this improvement because I don´t find a other solution. For me it was not possible to do the job about the camshaft and guide´s. I give this work to "Nockenwelle.de" Mr. Müller did a fin work and it works since 2004.

The other 2 times I have to open, it was the drive gear of the distributer. (So much thanks to Hannelore and Dirk for the two parts, one of them it was the spare part of Dirk).

Little story

Kai

 

[Montikai]

here a picture of the distributer drive gear