[Corwin]

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[IRONBLOCK]

Hi Corwin,

So sorry to hear of the issues with your Montreal. Unfortunately I have the same issues with my car and learned that the engine was rebuilt two or more years prior to my purchase. As I understand from my experienced Montreal engine re-builder, the same head gaskets (from MrFiat (or I believe Spezzio)) were used for another car and it exhibited 'fire ring deterioration'.

after a spirited drive I noticed the temperature gauge approaching 100C and coolant overflowing the reservoir when the engine was turned off, so perhaps the gaskets failed. When checking head nut torque only about 30 ft-lbs were required to loosen the nuts prior to oiling and re-torquing them. They were torqued to 67 ft-lbs or so as suggested in Montreal the Essential Companion but the bubbling continues. MtEC suggests other reasons for coolant loss but I believe you've checked off all of them. When performing the chemical 'Block Test' my engine was 'fine' -until turned off, at temperature, at which point bubbling became very pronounced and the block test chemical shifted to show exhaust gasses bubbling up out of the overflow reservoir. They could only come from the engine...

Despite the failed block test, there is no oil in the coolant or coolant in the oil. After each 30 minute drive or so, I check and use a radiator cap tester to pump coolant back from the overflow reservoir into the thermostat housing (with caps removed). If I didn't pump the coolant back into the radiator, eventually the coolant level would drop below the temperature sensor in the radiator, which would most likely prevent the fan from coming on and cause overheating. In my case, I know that at least the head gaskets need to be replaced. I have put off this major job for a couple reasons; mainly fear of the Spica and fear of finding heads that need expensive (crack) repairs. I have purchased new gaskets from "Gaskets to Go" and Reinz (I think).

Mark

 

[Corwin]

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[mtbjeff]

I think that the head gaskets or cracks is a likely cause for this overheating and just not showing up with a chemical block test for hydrocarbons in the coolant. If the Water Pump as not been rebuilt recently I would seriously consider removing the engine from the car and rebuild the water pump while the cylinder heads are removed.

I just finished dealing with a Triumph TR6 that could be driven around town for an hour without overheating but as soon as you started driving at highway speeds or in the mountains it would start overheating. The head gasket was not sealing well.

On another note here is a Gates part number for a 160 degree or 71 Cel. Thermostat for the Montreal engine

 

[divotandtralee]

If there is documented history these heads can have mini-cracks..I would follow that course and rule out the gasket thing. A failing gasket would show throughout the temp range IMO..The engine temp rises when you shut down thus expanding crack. I would pressure test under heated conditions.. http://www.performanceheadengineeri... pressure test a,the cylinder head is leaking.

 

[IRONBLOCK]

Corwin, if you have not already tried it, it might be worth the effort to re-torque the head nuts on your engine. Shazz (Steve) had luck doing this on one or two of his Montreal engines. Also, Bruce Taylor states that "A minor gasket leak may cause a continuous stream of bubbles in the coolant reservoir when the engine is running. However, bubbles can also be caused by air in the coolant circuit if a malfunctioning filler cap valve prevents coolant returning from the reservoir to the engine after it has stopped" -this is harder for me to visualize but I understand that a malfunctioning cap or even a loose hose clamp on the return line would allow coolant to leave the engine but not get sucked back in when returning to room temperature. I understand that you've replaced the cap with a higher pressure cap. I did the same thing and it did noticeably increase pressure in the lines but the issue remains.

Ric, you are right. My car exhibits very slight bubbling while it is running but when the engine is switched off, the bubbling in the overflow increases significantly. If the coolant reservoir is more than one inch above the 'Min' line, cool; when hot the coolant will overflow the reservoir upon switching off the engine. (Page 103, in MtEC covers bubbling in the reservoir and compression testing)

Like Jeff suggests, if the engine is removed it presents an opportunity to up-date the water pump. I spoke with Delmas Greene last week and he strongly recommends the water pump modification Bruce describes in MtEC. Eliminating the highly stressed and complex loaded outer ball bearing (that is working at nearly 100% of its design load) on the water pump shaft and replacing it with a roller bearing -that has nearly 10 times the load capacity AND drilling a hole in the front cover as shown to allow lubrication of the bearing. Delmas has done this modification to 5 or 6 of his Montreal's and has not experienced a failure since; in over 25 years! (Pages 59 and 63).

Mark

 

[divotandtralee]

Hey, guys.. I tend to wade into territory I don't belong in .. Don't know Montreal engine other than they are V-8's

 

[robo330]

I have removed my engine and rebuilt it. What I originally thought was a Head Gasket failure turned out to be a Water Pump Bearing / Seal issue. If it comes to this, I suggest removing the engine and doing the re-build on the bench. But, before you go down that route, check your Cylinder Head Nut Torque. With the engine cold, loosen and re-tighten the Cylinder Head Nuts doing it in the "correct" sequence. I would Torque the Nuts to 65 ft/lbs first and then take them up to 70 ft / lbs. Leave overnight and re-check the Torque. If you still have the same problem, it's probably time to get the engine out. It's not such a big deal. There are a couple of threads here about it, so take your time and do it right. Some people may be worried about cracked cylinder heads. I would not jump to that conclusion right off the bat.
Yes, a good set of Head Gaskets make a big difference. They should not have been on the shelf for a long time. New Head Gaskets are available from Classic Alfa or Alfaholics in the UK. 3 days from time of order to delivery. Good Luck! By the way, do you have a Cylinder Head Nut Tool available?

 

[Corwin]

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[divotandtralee]

Might as well if the water pump hasn't got a history.. from little I know

 

[robo330]

With the Water Pump it's not about any history. As a number of us know, the Bearings, Spacer and the Seal has been under stress for more than 40 years. It's not a matter of not failing, it's a matter of when it will fail. Unfortunate piece is that to remove the Water Pump and the Front Cover, you have to remove the Cylinder Heads. That is why most people will tell you to pull the engine out and rebuild it on the bench. This allows you todo the modifications to the Water Pump and the Front Cover, Cross Drilling the Oil Holes to better lubricate the Water Pump Bearing.

 

[Corwin]

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[IRONBLOCK]

Thanks for the update Corwin. Congratulations on getting to the root of the problem and getting Montreal repaired. When you changed the water pump bearing did you go with roller bearings or continue to use ball bearings?

Remember to retorque the head nuts as prescribed and take it easy until the heads are well seated.

Mark

 

[1750GT]

..... when we inspected the heads: small cracks at various spots on both sides. ...... I had the heads refurbished completely, welding of the cracks...

Could you elaborate on where exactly you found the cracks? It might be helpful for others (like myself) who will be going down the cylinder head & engine rebuild route in the near future (hopefully). I read on Bruce's website that he mentions the areas around the spark plug holes as being prone to cracking.

 

[Corwin]

Could you elaborate on where exactly you found the cracks? It might be helpful for others (like myself) who will be going down the cylinder head & engine rebuild route in the near future (hopefully). I read on Bruce's website that he mentions the areas around the spark plug holes as being prone to cracking.
[/QUOTE

 

[Corwin]

With the Water Pump it's not about any history. As a number of us know, the Bearings, Spacer and the Seal has been under stress for more than 40 years. It's not a matter of not failing, it's a matter of when it will fail. Unfortunate piece is that to remove the Water Pump and the Front Cover, you have to remove the Cylinder Heads. That is why most people will tell you to pull the engine out and rebuild it on the bench. This allows you todo the modifications to the Water Pump and the Front Cover, Cross Drilling the Oil Holes to better lubricate the Water Pump Bearing.

Indeed, have a look at what the bearing looked like when we this was opened up before the refurbished heads were reinstalled.

Thanks for the update Corwin. Congratulations on getting to the root of the problem and getting Montreal repaired. When you changed the water pump bearing did you go with roller bearings or continue to use ball bearings?

Remember to retorque the head nuts as prescribed and take it easy until the heads are well seated.

Mark

 

[robo330]

It’s a little late now, but it doesn’t look like you drilled the oil supply holes in the Front Cover. They certainly add to the longevity of the Bearings now. If you haven’t done it, don’t worry, I don’t think your car will be doing a lot of mileage in the next few years. Personally, I followed the instructions as per Bruce Taylor’s book, as have a few other people I know on our site. Just mentioning it…

 

[classicalfas]

He mentioned sealed bearings where installed.

 

[robo330]

I guess that means he won’t need the extra oil feed…?

 

[robo330]

Seeing you mentioned it Peter, what’s the better replacement? Sealed Bearing and no extra oil feeds or Unsealed Bearing with added Oil Feeds?
6 of one, half a dozen of the other? Interesting to hear the different opinions…