overheating 1600 twink

[sparkey]

Can anyone advise on why my 1600 twin cam gets so hot?

 

The temerature sits at about 90 - 95 degC most of the time, and if driven lightly it stays at that. If I take it for a proper thrash, it also almost manages to stay out of the orange, but when I slow down after some fast driving it goes straight into the red and boils over (This is actually in an Elan, not a 7). The car has a new water pump, newish radiator and I have flushed the cooling system which appears to be clear. There is no water in the oil or vice versa and power seems up to standard, so I think (hope) the head is OK.

 

I carried out a compression test and found cylinder 1= 200, 2=195, 3= 180, 4=180 (PSI approximately with engine fully hot, throttle open etc.), which isn't great between cylinders but seems high enough to suggest that the head is not leaking pressure to the water system.

 

Any ideas of what else I can try before taking the head off for a look?

 

Thanks

 

Sparkey.

[deanteam]

Hi Sparkey

The only thing I can suggest is that if you don`t use a swirl pot to put one on to make the water capacity biger, or to fit an oil cooler. When I use my twin cam on the track the oil can easy reach a temp. Of 130°-135° but the water stay`s at around 80°-90°. After useing it like this I try to run a couple of moments slow that the oil gets down, I run it with no oil cooler but a swirl pot.

 

[R2D2]

I have a Twin Cam in a Seven and it runs at about 75deg C with a 72deg C thermostat fitted even in the current weather. I do have the large Caterham Radiator fitted, which probably helps compared to the relatively small rad. fitted to the Elan.

 

I would think that it is quite normal for the temp. to increase slightly after a thrash and if the cooling system is marginal it may push some water out.

 

There could be a problem with the new pump you have fitted, which may have reduced flow. I had quite e few problems with my engine last year and bought 2 QED water pump kits. The first one had a impeller with curved vanes and the second one had vanes that were straight. I queried the difference with QED and was told that they no longer produced the curved vane version and that the "straight" design gave enhanced flow.

 

The other important set up point of a Twin Cam is the clearance between the pump impeller and the pump housing. If the gap is to small the waterflow will be reduced.

 

The problem is that to check this clearance the head has to come off any way.

 

I would start by checking the stat. works at the correct temperature or fit a new 72degC stat.

 

I checked my head for leaks using a "Block Tester" that I bought from Snap-On for £40. and is a bargin for peace of mind.

 

Good Luck.

 

[sparkey]

Thanks for the replies,

 

I've actually removed the thermostat at present so it's not that, but I'm beginning to suspect the water pump because the problem has got worse since it was replaced. I don't know what the clearance is as I had the work done by someone who claimed to know what they were doing. I also don't know if the vanes are straight or curved.

 

Any idea where I can get this "Block Tester" thing - do snap-on have a mail order service in the UK? Sounds like a useful piece of kit.

 

I think the main problem is that my wife has been using the car as a daily commuting car for a year or 2 and it never really got above 4000 revs, so the problem may have been around for a while and she just didn't notice. I've now taken over the car and have been driving it with some enthusiasm, which has highlighted this (and other) potential problems. I think the head will ultimately have to come off for a general look inside anyway. I'm used to Crossflows in my W*******d, and these modern twin cam things (OK so it's 1970) scare me.

 

Thanks

 

Sparkey

[R2D2]

I 'phoned my local Snap On Agent (Van Salesman) and he delivered one the next day.

They have a website in the UK and the office should give you the relevant 'phone number.

Miles Wilkins book on the Twin Cam engine is quite useful and had just been re-printed with some more information than the original version. probably worth £25 if you are going to stick with the Twin Cam.

 

 

[sparkey]

Thanks Chris,

 

Found the Website last night and will try and get the kit this week. The book sounds like a good investment as well as I can see I may be doing some work on this engine.

 

Sparkey

[tony isherwood]

Problem sounds similar to that I had with an escort, OK' ish in normal conditions but boiled at the slightest hint of any exertion. Replaced the waterpump and all problems were gone.