Intermittent Overheating Problem

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cheshirecat
Posts: 20
Joined: Wed Apr 08, 2015 9:04 am
Location: Cheshire

Intermittent Overheating Problem

Post by cheshirecat » Fri Aug 07, 2015 10:53 am

GRC seems to be suffering with an intermittent overheating problem. Sometimes she runs fine, sometimes she seems to overheat in an instant. I'm struggling to diagnose the problem.

The story so far ...

When I picked her a couple of weeks ago the fan belt gave way after 100 miles and she quickly overheated. The AA had a look, managed a temporary fan-belt fix and we drove a further 50 miles with the temp gauge happy at 85 deg C

After a few failed attempts I managed to source a new fan-belt on Tuesday. Took her out for a test drive after a quick top up of Bluecol coolant and everything was sweet for 15 miles. Drove her down to the garage (6 miles) that evening with no problems. Even with a quick blast up to 95mph (naughty, naughty!)

Picked her up on Wednesday evening after a service and she managed to overheat in the 6 miles back home.

Topped her up with fluid yesterday and drove her back to the garage this morning. No problem at all. But on the way back after a cooling down period she was on the verge of overheating after 6 miles.

I know the bearing in the water pump has gone and I've ordered a replacement from Sunbeam Spares. I will also replace all of the hoses.

The radiator looks relatively new, but I'm concerned that after a long period of inactivity, maybe it's not as good as it looks. I'm happy to replace the radiator if necessary. There are no obvious leaks from the radiator, but I'll have another look when it's cooled down.

I have a six-bladed metal fan and an electric pusher fan on a manual switch.

I'll post some photos of the set-up this evening.

Any advice would be welcome. If I need to completely re-do the cooling system, I'm happy to do so and would appreciate some guidance.

Thanks

Doug

bigbob
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Joined: Wed Aug 19, 2009 11:31 am

Post by bigbob » Fri Aug 07, 2015 3:05 pm

Welcome to joys of Tiger ownership. You don't have problems, just challenges to solve!
Does it actually over heat, or does just the gauge read high? Sometimes a loose connection on the sender can cause false alarms.
You may find debris has settled in rad after long standing. It might be sorted by a flush through. A rad specialist should be able to test it before expense of buying a new one.
Alloy rad & electric fan should solve any over heating for long term future.

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cheshirecat
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Joined: Wed Apr 08, 2015 9:04 am
Location: Cheshire

Post by cheshirecat » Fri Aug 07, 2015 3:16 pm

Thanks bigbob

I'm fairly certain that the gauge is okay. It is proper overheating ... you can hear it boiling away.

I will flush the rad out over the weekend to see if that improves things.

Mal
Posts: 668
Joined: Sat Aug 02, 2008 5:39 am
Location: NZ

Post by Mal » Fri Aug 07, 2015 9:13 pm

I would start with the thermostat. Take it out and run the car without it for a while. Take it for the same drives where it has overheated and see if it still does it.
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Tim
Posts: 75
Joined: Fri May 06, 2011 4:00 pm
Location: Wiltshire

Post by Tim » Sun Aug 09, 2015 9:17 pm

Hi Doug,

On my Tiger I had an overheating problem which was due to the inlet hose into the water pump becoming weak and collapsing when the engine was running at higher revs. Easily checked by watching the inlet hose whilst revving the engine.

Brad1380
Posts: 473
Joined: Wed Apr 27, 2011 1:38 pm

Post by Brad1380 » Mon Aug 10, 2015 6:19 pm

Isn't there supposed to be a spring in one of the radiator hoses to stop it collapsing?
1966 Sunbeam Tiger Mk1a

Tim
Posts: 75
Joined: Fri May 06, 2011 4:00 pm
Location: Wiltshire

Post by Tim » Mon Aug 10, 2015 6:44 pm

There certainly is in a SBF Mustang, but not sure if the Tiger ever had one fitted. A modern silicone hose appears to solves the problem without a spring, on my Tiger at least.

Mal
Posts: 668
Joined: Sat Aug 02, 2008 5:39 am
Location: NZ

Post by Mal » Mon Aug 10, 2015 7:30 pm

I think the spring was on the lower hose of LHD MODELS AS THERE IS NO ELBOW THE HOSE IS LONG.
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tigertim
Posts: 81
Joined: Mon May 25, 2015 11:06 pm
Location: Kent

Post by tigertim » Wed Aug 12, 2015 11:30 pm

Hi Cheshirecat. I got my Tiger back in Feb. when I bought it I knew it had a leaky Header tank, so expected to do some work. I scrolled through most of the tec forums to see what overheating probs guys had over the years. what I found was that if you have a pretty stock car(as is mine) with a original rad, its likely to be half full off rust. It was. Don't mess take it to a good rad repair shop if you want to keep it original,and have it re-cored. Mine had 90 cores and was rebuilt with 148 cost £300 or buy new. If it is full of rust, do the matrix as well (£68 from SBS) and replace all the pipes, stat and my stat housing had rooted out as well, make sure you drill a small bypass hole in stat, some come with a hole and giggle pin, mine had neither from Real Steel.

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cheshirecat
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Joined: Wed Apr 08, 2015 9:04 am
Location: Cheshire

Post by cheshirecat » Thu Aug 13, 2015 11:39 pm

tigertim wrote:Hi Cheshirecat. I got my Tiger back in Feb. when I bought it I knew it had a leaky Header tank, so expected to do some work. I scrolled through most of the tec forums to see what overheating probs guys had over the years. what I found was that if you have a pretty stock car(as is mine) with a original rad, its likely to be half full off rust. It was. Don't mess take it to a good rad repair shop if you want to keep it original,and have it re-cored. Mine had 90 cores and was rebuilt with 148 cost £300 or buy new. If it is full of rust, do the matrix as well (£68 from SBS) and replace all the pipes, stat and my stat housing had rooted out as well, make sure you drill a small bypass hole in stat, some come with a hole and giggle pin, mine had neither from Real Steel.
Thanks for the info. Mine is a stock 260 as well. The overheating is no longer an intermittent occurrence. But it was dropped off at the garage this evening with all of the parts to completely renew the cooling system ... Rad, stat, water pump, hoses, a new fan shroud, etc.

I'm hoping when I get back from our weekend in Wales the overheating problem will have been resolved.

Then I can move on to the misbehaving carburettor!

tigertim
Posts: 81
Joined: Mon May 25, 2015 11:06 pm
Location: Kent

Post by tigertim » Fri Aug 14, 2015 11:32 am

Doug. Had probs with my carb as well Holly 4 pot, the secondary weren't kicking in, Choke cable was jamming the diaphragm rod, also needed a new diaphragm. and the throttle was bottoming out on the carpet so it wasn't opening enough to create a vacuum to open them. Also had to adjust idle air screws on either side of front of carb to get tick over correct.
I also have a spare Header tank if you require. I had three made. Spun in aluminium to look like original. PM me if you interested
Tim

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