[bug71]

Hi all I have a 1971 1200 bug running a 1600 twin port engine with a pair of weber ICT carbs all bolted to a 1200 gearbox and I've been fighting an over heating issue for a year now since I brought it.
Long story short, she is fine under 50mph, as soon as I go 50 mph of above the oil temperature slowly but surely gets hotter and hotter, the faster I go the quicker the oil temp rises but I've never allowed it to go above 130⁰c on my gauge and that's when the save my bug dip stick triggers the warning light.

Now some history, at first it had a solid deck lid and this would send the oil temperatures up to 130⁰c if I went over 50mph.
I now have a 4 slotted deck lid and that dropped the oil temperatures down to 120⁰C max at any speed over 50mph.
I've now fitted top stand offs and this morning (first drive with them on) the oil temperature only got to 82⁰c.
What is this telling me?
All tinware, seals, fan shroud cooling flaps and bellows are fitted and working correctly, the carbs are jetted a little on the rich side but all carb adjustment settings are still with in spec.
No rubbish is in the cooling fan, dog house parts are all there.
I don't want standoffs but if I don't have them fitted I over heat, please help
PS I have a SVDA distributor fitted and I've tried timing settings from 28 to 32 BTDC but it made no difference to the oil temperatures and I'm running nine a 30 weight oil.
I also have 45psi @70⁰C oil temp @ 2500rpm so oil pressure seems OK but any thing over 110⁰C oil temp does bring the oil warning light on at idle
Cheers all

 

[keekster64]

If you’ve not already checked out the articles on way out westy site on running Ict carbs then I recommend you do. It’s not clear what driving you subjected the engine to when running standoffs compared to just a 4 grill lid. I wouldn’t have expected much difference. If you can’t get it to run cool enough without the stand-offs one option is to cut a hole in the fire wall and duct it to above the gearbox. I did this on my 64 so I could run a stock lid with my 1776.

 

[bug71]

Yes I have read his website about running 34 ict carbs. On the website he is saying to run 55 idle and 140 mains if I remember correctly but that was way to lean. I had to run 60 idle jets and 165 mains to get my engine to work.
All the driving for the results I got was on the Same dual carriage way sitting at 60mph for 30 minutes. With the solid lid I had to lower my speed to 45 mph to keep the temperature below 120⁰c, with the four vented lid I could do 55mph and keep the oil temperature at 120⁰c and with stand offs I once again maintain 55mph but the oil temp only hit 82⁰c
But saying that it was only 16⁰c outside when I did this run where the othere two runs it was 22⁰c outside
When you say fire wall are we talking about the bell housing tin wear

 

[GARRICK.CLARK]

Yes. The tin at the back. Have you checked to see if the thermastat is fully operational and fully open at running temps.

 

[bug71]

Yes mate the bellows are opened fully up and the flaps inside the fan shroud are fully ope as well

 

[GARRICK.CLARK]

Is there a stainless exhaust on it. They can heat an engine up no end. Oily crud inbetween the head fins will do it too. At what rpm would you say your doing at speed over 50mph. A 1200 ratio box isn't ideal for motorway cruising.

 

[bug71]

Stock exhaust system with stock heat exchangers is what I'm running.
In four gear I think 2600 ish rpm to do 50mph, 3,200 rpm is about 60mph and 3800 rpm to do 70 mph.
These figures are what I can remember so that will nit be spot on

What should the cruising speed rpm be on a bug

 

[GARRICK.CLARK]

My opinion is 55 with a 1200 box. 70 with a GT box. This is with factory rear tyre size. Is your fan housing a factory one. The copy ones make a motor run hot as well

 

[keekster64]

Yes I have read his website about running 34 ict carbs. On the website he is saying to run 55 idle and 140 mains if I remember correctly but that was way to lean. I had to run 60 idle jets and 165 mains to get my engine to work.
All the driving for the results I got was on the Same dual carriage way sitting at 60mph for 30 minutes. With the solid lid I had to lower my speed to 45 mph to keep the temperature below 120⁰c, with the four vented lid I could do 55mph and keep the oil temperature at 120⁰c and with stand offs I once again maintain 55mph but the oil temp only hit 82⁰c
But saying that it was only 16⁰c outside when I did this run where the othere two runs it was 22⁰c outside
When you say fire wall are we talking about the bell housing tin wear

No, not the tinware, the actual bulkhead. I fitted a stainless tube through it to duct air up from above the gearbox. I still think something else is creating a heat problem. If the tinware is all in place and you are running a genuine fan housing I’d look a little deeper. When I bought my current 1600 project engine I found a number of issues, in particular the heads had a lot of flashing that was blocking the fins around the exhaust ports. My brother drilled them out. It would have caused overheating issues. We also found the exhaust value seat on one valve was not cut properly and the valve out have not been closing properly. This would have also caused hot running issues. I’m not saying you have these problems but it demonstrates how small flaws can create puzzling problems of running too hot. As for revs, I find running 165 tyres 70mph is 3500 on a 1200 box.

 

[callookoval]

Timing set at 28 /32 degrees full advance? Is this with the vacuum disconnected and plugged? Have you checked to see what the advance is with full vacuum?

 

[bug71]

This is the only photo of the fan shroud I have.
Yes 3500 or just a little over is 70 mph and I'm running 165/80 tyres.
Yes 28 to 32⁰ BTDC vacuum lune disconnected and around 44⁰ with it connected at max advance which it just over 3000 rpm and stays at this figure up to 5000rpm. I will have a look at the cylinder heads and check the fins are not bloked. How can I check the valves are setting correctly?

 

[bug71]

Here's the only photo I have of the engine bay. Can anyone see anything wrong except for the missing air filters

 

[callookoval]

Time it correctly at full advance with the vacuum hose plugged.

 

[bug71]

Time it correctly at full advance with the vacuum hose plugged.

I believe I have timed it correctly. I removed the vacuum hose and plugged it, increased the rpm to the point where the distributor stopped advancing which just over 3000 rpm, using my timing gun I set the timing at 28⁰BTDC at first and over time have slowly advanced it to 32⁰ BTDC.

 

[callookoval]

Ok. Do you by chance know what pressure relief spring is fitted? Is it just a stock one? If you have timing correct, carbs have been jetted and tuned etc then it could be that your oil is bypassing the cooler for some reason.

 

[bug71]

I have no idea what pressure relief springs are fitted. All I can say is that at 100⁰c oil temp I have 10psi per 1000rpm.
Should I go and buy a set of after market high pressure ones ?
Also should I have the plan type pistons of the ones that lime like a top hat?

 

[callookoval]

I have no idea what pressure relief springs are fitted. All I can say is that at 100⁰c oil temp I have 10psi per 1000rpm.
Should I go and buy a set of after market high pressure ones ?
Also should I have the plan type pistons of the ones that lime like a top hat?

Are you able to remove the spring and post a photo of it?

Also, before you fitted the save my bug, did you check it in boiling water? How do you know for sure that you're actually getting 130C?

 

[bug71]

Yes I calibrated the save my buy in cooling oil to get the temperature up nice and high.
No I don't have high pressure springs in it at the moment, they are both stock and I have two plan pistons on them. I'm wondering if the engine to worn cause at idle (900 rpm)
The warning light does come on solid when up to temperature but at 1000rpm the pressure is back up to 10psi and I do have tbe 10 psi per 1000rpm, it's just at idle I have low pressure. Please Inlight me on something, if I was to fit heavy duty springs will that direct the oil to the cooler earlier?

 

[callookoval]

Yes I calibrated the save my buy in cooling oil to get the temperature up nice and high.
No I don't have high pressure springs in it at the moment, they are both stock and I have two plan pistons on them. I'm wondering if the engine to worn cause at idle (900 rpm)
The warning light does come on solid when up to temperature but at 1000rpm the pressure is back up to 10psi and I do have tbe 10 psi per 1000rpm, it's just at idle I have low pressure. Please Inlight me on something, if I was to fit heavy duty springs will that direct the oil to the cooler earlier?

Sorry, I misunderstood that last post. The rear spring controls where the oil goes (to the cooler or bypass). The front spring (dual relief cases) controls oil pressure so only it can cause excess pressure but that is not your issue.

Are you sure the springs are stock because a couple of posts up you say you had no idea whether they were stock or not. I'm not trying to be a dick, just checking

Seeing the low pressure warning light flickering occasionally at hot idle is not necessarily a sign of something off. Our pressure switches come on very low. Are you sure the oil pressure switch is good?

I'm still not sure I'm totally convinced that you're actually seeing 120C genuinely.

Whereabouts are you located?

 

[bug71]

I'm in Oxford mate. I can check the relief springs and have a look, or should I just replace with new stick springs ?
They don't cost a lot at all.
I've just ordered a new pressure switch from vw heritage that operates at 0.3 bar/ 4.4 psi.
My light is not just flickering at idle it's on solid but goes out at 1000rpm and I have a reading on my dash gauge of 10 psi.