• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

BJ8 Overheating

Share this page

Just a brief scan on this thread.

Has anyone checked the flow of the water pump? Is the pump stock? Has the impeller to base and housing clearance been checked? If you're not getting good coolant flow, all else will just be "patching" it.
 
Ron's question brings up another that I have,

Does anyone make an " upgraded " or higher flow rate water pump that fits the big Healey ?
I don't think I have ever seen this mentioned here but I should ask in case someone knows something.
 
Hi Ed,
I'm not sure that the cars would gain much from a higher flow pump. It really doesn't have much effect on things. It would maybe build a little higher localized pressure in the block & head for "some" benefit. The easiest thing to try would be a smaller diameter pump drive pulley. I guess if the low flow problem were only at idle, a faster idle speed might also help.

Ron - I think the pumps have to have quite a bit of rotor to housing clearance, maybe .030",(pumping loss) to prevent cavitation at high rpm. The typical automotive pump is around 20% efficient. They have to cover a much wider rpm range than an efficient single speed pump does.

One reason for the thermostat restriction is to increase the localized pump output pressure which also increases the pump suction side pressure. This raises the pressure in the water jackets (good) & also raises the pump inlet pressure to reduce cavitation (good). Note - These localized pressure differences are not the same as the overall system operating pressure.
D
 
Hi ED , Yes you can gain a small amount of improvement by speeding up the pump. It may be a bit costly depending on what width vibration damper you have on the car. What I have done is install a 3/8" damper on the car and then run a pump with a 1/2" pulley on it. Most of the pump problems I have seen with the aftermarket units is the rotor is positioned incorrectly. The factory manual calls for a 0.015" spacing while I have seen them from the vendor at 0.050". Its easy to close em up using a feeler gauge.---Fwiw---Keoke
 
I understand your argument Ed. But has anyone MEASURED the flow volume, and pressure? That's my question. If there is a problem there, then first place I would be going is after the pump.

Pump impeller design has changed quite a bit from the production days of 50-60's LBC. Where a 4 blade shallow straight impeller was used, most modern pumps use a curved 5 or 6 blade impeller, the curvature and depth of the blade has an affect on controlling cavitation.
 
I had an overheating problem on my BN7. Turned out to be the radiator cap. Most aftermarket caps, although correctly rated, are not long enough between the cap and the pressure seal. The rad heats up but does not pressurise and quickly boils - normally throwing a lot of liquid out of the overflow pipe. Have a check, could be a cheap cure - was for me.
 
specialsports said:
I have checked the temp gauge all is OK. I think the main problem is being a highly tuned engine it gets very hot within the engine bay and no way to get this heat out. The Kenlow does help a little. Still waiting for new 123 dizzy, new thermostat and I am going to try this Water Wetter! I will give the cooling system a good flush out before above. Once I get this fitted I will let you know if a success or not.
Brian
Click to expand...

Remember water wetter works best with a 10%/90% solution of antifreeze/distilled water. Put in the very least amount of anti-freeze necessary to keep your block safe in the wintertime.
 
RonMacPherson said:
Just a brief scan on this thread.

Has anyone checked the flow of the water pump? Is the pump stock? Has the impeller to base and housing clearance been checked? If you're not getting good coolant flow, all else will just be "patching" it.
Click to expand...

Higher coolant flow won't necessarily help. If you push water too fast through the radiator then it will be going back into the motor hot, rather than cold. The issue usually isn't speed of flow, but one of cooling efficiency of the whole system.

A sleeved thermostat isn't a "patch" by the way, it is what the austin head is designed to use...
 
Ah, but what PRESSURE is the pump putting out? FLow is composed of two components, volume and pressure.
 
OK The whole rad and engine has now been flushed out, nothing abnormal found. New pump fitted, also a new 160 thermostat fitted after finding I had not one in at all.
This would have made hot spots in the engine, also the water would be circulating so fast through the rad it would not have had time to cool, also the pump would be working too fast with the flow not being restricted with no stat fitted. I have now refilled with pure water and antifreeze at a slightly lower mixture and added some Water Wetter. This has resulted with a much cooler running engine.
I think I might have given a false impression, the engine heat within the engine bay was the main problem and not the water temperature, although it can get high on a hot day if driven hard. My main problem is now finding a way to cool down the engine bay or getting the heat generated within out?
I have just had a 123 dizzy delivered last week, it went straight back to the supplier the following day! Why? After changing the polarity and luckily I had the sense to put a mark on the old Lucas dizzy and clamp plus body in case of any problems with the 123!! I could then change it back.
After taking out old dizzy fitted 123 all as instructions given, started engine, it ran for 30 seconds then gave up, after that the engine never fired up again with the 123 fitted, I even had a 123 Specialist guiding over the phone. Now normally my engine aways fires up 2 try even with a half flat battery and a worn out dizzy. The 123 was then taken out and my old dizzy of 40 year's old refitted to the marks I had made, and yes you guessed it, fired immediately. My supplier was contacted and I was asked to send it back, for a refund. I was informed by them that they had been having a lot of trouble with the 123 for BJ7 & BJ8! but I suspect it is a lot worse and other models are involved from what I have since found out?
I have been in touch with a few of the Healey racing people here in the UK and they just laughed when I asked them what they thought about the 123! Too unreliable I was told, also if they decide not to work they cannot be fixed easy, and definitely not at the road-side. You can aways get an old Lucas dizzy to work if you carry a few spare parts.
However I have now rebuilt my old Lucas dizzy and it is well packed and safe in the trunk should I need it.
In it's place after much liaison with the racing fraternity, I fitted a Mallery, that is what most if not all racers use in the UK, very solid piece of kit, it is mechanical and not a mini computer like the 123. I have re-tuned my engine to it, so far I am very impressed, I think I might change the condenser to a Lucas and keep the Mallery condenser as a spare.

https://i21.photobucket.com/albums/b287/vvs393/P72800088.jpg
https://i21.photobucket.com/albums/b287/vvs393/P2210005.jpg
 
Well Brian, Just how cool did it get??---Keoke--AZ-- /bcforum/images/%%GRAEMLIN_URL%%/cowboy.gif
 
Hi I would say it is at least 10 - 15 degrees cooler. It now runs at around 170. Then after a long run and just parked up the temp will rise to 190 and a bit above. That is why I have the Kenlow fitted it kicks in over 190 or if stuck in a traffic jam. My next job to do this winter is to rap the comp manifold, I have already attached the heat restricting sheets under the bulkhead.
Brian
 
Hey!, that temp range sounds good Brian. It is about the same as mine runs. Be a bit careful wrapping the manifold. I understand it can accelerate wear out of these units.---Keoke- /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
 
Rather than wrapping the manifold, you should get it ceramic coated, like jet hot coatings...
 
I have ceramic coatings on my original manifold as well as my headers. Jet Hot claims up to a 70°F temp drop in the engine compartment. I never coated the downtubes and wondered if the coating would work well with the flex tubing portion of them. One thought is to cut the flex tube off, Jet Hot coat the manifold and remaining down tube. Then install those stainless woven exhaust hoses Dave Russell suggested a while back in another thread. YMMV.
 
I think the Jet Hot coat treatment is the thing for your headers. Wrapping anything is the engine bay is a potential issue if oil ever gets on it because it could become a fire issue. Some of the new cars have a mirrored stainless steel surround for the exhaust and I wondered if something like that might help a big Healy's heat issues.
 
Back
Top