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Go Back   Madabout Kitcars Forum > Mad Build Area > Marlin 5exi builds

Marlin 5exi builds Calling all you sexi builders....sorry 5exi builders, show us your progress.

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  #1  
Old 23rd July 2009, 00:26
Gowles Gowles is offline
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Question Rover Turbo 5exi overheating

Hi Everybody!

Having joined the forum a while back I think that it's about time to overcome my shyness and introduce myself...... AND admit that I would really appreciate some assistance from the enormous pool of 5exi knowledge and experience!

I bought my 3-year-old 5exi earlier this year from a guy who had bought it from the builder, who has apparently left the UK for France....

It's a fairly tidy example in grey gel coat, fitted with the 2 litre Turbo Rover engine, controlled by an Autronic ECU, with the intercooler in front of the rad and an annoyingly vented-to-atmosphere dump valve!

I've got the handling to an acceptable level (for reasonably fast road use anyway!), by tightening the loose tie-rods, replicating Elise track & camber front & rear and balancing the corner weights.

The bodywork finish is coming along nicely now and just needs a few days of elbow grease to get it looking as good as gel coat ever will.

My one outstanding problem is that of COOLING, or rather the lack of cooling!
The car runs an electric water pump, which is now on full speed constantly since I removed the variable control which had become totally unreliable.
The thermostat has also been removed and I have fitted the biggest fan that I can find to the rad, controlling this with one of those old-fashioned variable thermostats with a capilliary dangling in the "top hose" to the rad. The pressure cap has also been replaced

The current situation is that, when idling or being driven gently, everything behaves properly, with the fan cutting-in periodically for about 20 seconds to bring the temperature back down.

Sadly, anything more than about a minute of "spirited" driving causes a steep rise in temperature that seems to be beyond the capacity of the cooling system to cope with and clouds of steam ensue!

My current thinking is that the cooling system as it is simply isn't up to the job, so I'm planning to find the biggest rad that can be made to fit and to cool this with two fans. I'm also inclined to increase the diameter of the front/rear pipework and am wondering whether to squeeze a second rad with fan into the space behind the engine......

So, before I embark on a spending spree with the car breakers of Kent, I was wondering if anybody out there has a tried and tested solution to my problem?


Many thanks in advance,

Simon
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  #2  
Old 23rd July 2009, 06:33
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limpabit limpabit is offline
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Hi Simon.

Welcome to the forum.

I know John's (the origional build's car). Had big big power lump in it at one point.

First off. I don't think the size of the radiator is the issue. The reason I say this is that I ran a Rover turbo and had no problems with cooling or overheating. Could be a faulty rad though. The only time the fan came on for quite a while was while it was on the airfield day blasting round the track. But never over heated. Try flushing the system first off. Then I would try removing the front mount intercooler to see if that makes a difference (air flow etc). Just a couple of ideas.

The old dump valve issue. What ever one your get, it's going to be right behind the passenger ear hole! None are quite with a cone air filter. Came to the conclusion that either put up with the noise, or use the original air box (not the prettiest things!)

Your 5EXI was one of the original ones from Marlin. Since then, there has been quite suspension threads on this forum about upgrading the suspension because the car was deemed quite dangerous in certain situations. Mainly at motorway speeds, sudden slowing down would cause instability of the rear.

I noticed you said breakers in Kent. Do you live in Kent then? I'm only in Essex.

You could put you location in your profile.
<<<<
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Old 23rd July 2009, 08:48
5exiAdam 5exiAdam is offline
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As Limpabit said, flush the system.

What about something like WaterWetter, which apparently works by removing all the air bubbles, giving the water a much better contact with the radiator. A friend of mine swears by it in his little track car. May be worth a squirt???

Alfa 156 V6 Radiator is very efficient and think it will fit quite nicely. I have one somewhere and was going to try it on mine. It has a double fan and asimple 3 wire connection.
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  #4  
Old 23rd July 2009, 08:50
5exiAdam 5exiAdam is offline
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The other thing to possibly check is the fueling. If the ECU is not setup 100% your mixtures could be all over the place.
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  #5  
Old 23rd July 2009, 09:01
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eaa53 eaa53 is offline
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When John built the car he replaced the rear cross beam support as well as fitting an ARB at the rear, so there should be some improvement rigidity over the rest of that series chassis.

There are still improvements that could be made as it has the original uprights with the inherent 40mm between ball joint centres although as I recall he did level the ball joints.

The copper pipe plumbing John used could be easily replaced for larger bore pipe but it could be a lot of work for no good effect if Steve is correct.

If you have the capability to measure the inflow and outflow temperatures of the rad that may be indicative of problems in your case that would be easily achieved. Based on these readings air flow or blocked rad could be quickly identified as issues.


JohnC
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  #6  
Old 23rd July 2009, 09:05
5exiAdam 5exiAdam is offline
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Silverlinetools.com do an infrared thermometer for £40

their code is 633726
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  #7  
Old 23rd July 2009, 12:30
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SDMC001 SDMC001 is offline
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Simon

Welcome to the forum I have read yours and the other comments, and felt the all to be valid, I would just a few of my own for thought.

I have used the 2Litre t series rad on my car, albeit a 1600, the size was the same but I believe the cappacity and cooling ability due to the core maybe differant.

In the matter of removing the thermostat, although many years since I was in the motor tarde, I remember folks who took the stat out some times did have over heating issues. The rationale being that the water then did not spend enough time in the rad being cooled. Given you electric pump as well spining the water round fast, replacing the stat perhaps with a lower temp unit could be an option.

Steve
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  #8  
Old 23rd July 2009, 13:42
5exiAdam 5exiAdam is offline
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Quote:
Originally Posted by SDMC001 View Post
Simon

Welcome to the forum I have read yours and the other comments, and felt the all to be valid, I would just a few of my own for thought.

I have used the 2Litre t series rad on my car, albeit a 1600, the size was the same but I believe the cappacity and cooling ability due to the core maybe differant.

In the matter of removing the thermostat, although many years since I was in the motor tarde, I remember folks who took the stat out some times did have over heating issues. The rationale being that the water then did not spend enough time in the rad being cooled. Given you electric pump as well spining the water round fast, replacing the stat perhaps with a lower temp unit could be an option.

Steve
Good thinking!
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  #9  
Old 24th July 2009, 00:20
Gowles Gowles is offline
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Wow!

My sincere thanks to everybody for such a warm welcome and flood of advice!

Taking the points raised in some sort of order:

I forgot to mention that one of the first things that I tried was a flush and I was too embarrassed to mention that I really need to change the rad anyway, since I accidentally over-pressurised it by temporarily sealing the pressure cap on a Sunday afternoon when I couldn't buy a non-leaking replacement... This faux-pas also cost me a new electric water pump, as those plastic housings can't take too much pressure either!
(I have re-sealed the rad by re-crimping its aluminium "ears", but I don't trust it to stay sealed now!)

The intercooler location has been on my mind too, but presumably everything worked OK in this format originally? I will try moving it if the other ideas don't work though.

The dump valve noise issue is pretty much at the bottom of my current list of priorities, but I might consider a new valve, plumbed into the air intake if I still notice the noise once I've got things a bit cooler!

The handling seems acceptable to me as it is now, but I shall reserve final judgement until I get it on a track.... Again, not a huge priority just yet!

Yes, I do live in Kent.... just a few miles to the east of Sevenoaks.... I'm sure that I put my location in my profile, but I will double-check.

I like the sound of WaterWetter, but I'm sure that I shouldn't need it for road use, even with a bit of "spirited" driving! I will try it, but I don't think it's going to be a complete answer on its own.

The 156 V6 rad sounds like just the sort of thing that I had in mind. Is yours up for grabs Adam, or do you still plan to use it yourself?

ECU set-up is on the agenda, but the car only just squeaked through its MOT emissions test, so I don't hink that it's likely to be running excessively lean... Any advice on tuners with Autronic expertise within striking distance of Kent would be gratefully received!

Sucker that I am for gadgets(!), I'm going to have to get one of those infra-red thermometers.... Do you think it would work from the driver's seat if I run it without the bonnet???
On reflection, perhaps I should find a nearby rolling road....

As previously mentioned, the handling really isn't an issue for me as it is now, so it would indeed seem that the mods already made to my car have had a positive effect! Mind you, most of my RWD experience to date has been in karts and Caterhams, so I suppose that I'm not the best judge!

I don't propose to replace the original copper pipework since this appears to be no more than connection to the header tank etc.... The pipework that does give me cause for concern is the main front/rear (plastic) flow and return tubes and particularly a visibly partially squashed rubber hose between the underfloor tube and the sloping tube running up to the rad top hose....
(larger diameter tubes would also have the added advantage (to my mind at least) of increasing the total volume of coolant circulating... )

As previously intimated, I should shortly have the capacity to measure inlet and outlet temperatures, so we shall see what that shows up....

I can quite see the rationale of thermostat removal being counter-productive, but I only removed it after the over-heating problem had started. The EWP electronic control unit that should be used with the thermostat removed works by varying the pump speed from slow when the engine is cold to fast when maximum cooling is required.... That said, I fully intend to replace the thermostat with a lower temperature item as advised.... Once I know that it's not going to get too hot, I would prefer not to have to wait too long for the engine to get up to temperature!

One way or another I'm determined to get back on the road (and maybe track) while we still have some "summer" left, so I shall keep you posted on my progress or lack of it....
I shan't be doing much more than thinking about it for the next week as I'm away on holiday, but I shall crack on as soon as I return!

Many thanks to all once again,

Simon
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Old 24th July 2009, 07:13
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Ah your only down the road from me (about 30 minutes).

I'm sure John's car was working ok with the intercooler at the front. Just suggested this as part of the fault finding. But by the sounds of if, you may have found your problem.

Rover rad's are about £50 or so delivered. But it's a funny size.

http://www.madabout-kitcars.com/foru...light=radiator
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Old 24th July 2009, 11:50
Gowles Gowles is offline
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Thanks John!
You're right... we're almost neighbours! It would be good to hook-up at some stage and I'd love to see how you're getting on with your engine change, even though I just know that would sow some very expensive seeds of wanting my own "modern" engine! Anyway, I'll PM you my contact details....

I've ordered an RG302 from Advanced Radiators (currently £57.22 delivered next day) and I shall fit this, together with a low temperature thermostat and re-route / replace the deformed hose when I get back in the garage in August. Then fill and bleed the system and it's time to cross my fingers again!

The Alfa rad set-up could still be on the cards for a future improvement, but, if the current set-up used to work OK, the cheapest and most sensible option seems to be to try to restore the original status quo first.

Best regards,
Simon
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Old 24th July 2009, 12:04
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Hi Simon.

No problem at all. Would be good to meet up at some point. Might even if the weather is good, see Matt about in his 5EXI turbo.

Mine at the minute is nothing to look at ( though hopefully this will change within the next couple of weekends. As it's back in bits again at the minute.

You should be fine with the standard rad. Worked ok with mine.

When you refill the system, run the engine with the expansion cap off. Until the fan has cut in twice. This makes sure it has bled ok.

Also you may have ordered the wrong one.
Get Ad rad to measure the bottom mounting pins. 5mm may not sound a lot but it's the difference between fitting and not.
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Old 25th July 2009, 09:25
chrislandy chrislandy is offline
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Hi, when the Shelsley was racing a few years ago they initally had major overheating problems. During testing it would be fine but come the race it would overheat within 3 laps. The solution? If the front clam wasn't fitted right a piece of lower bodywork didn't get supported correctly thus the air bypassed the radiator.
Chris.
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Old 25th July 2009, 19:00
Gowles Gowles is offline
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Thanks Chris!
I really don't think that that's the reason for my problems, but, bearing your experience in mind, I shall have another look in that area..

Best regards,
Simon
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Old 26th July 2009, 20:27
5exiAdam 5exiAdam is offline
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Hi Simon,

I am planning to hang on to the alfa rad, just incase i need it for mine. Ebay should be able to source you one with fans for around 20 quid.

Infrared thermometer is so useful for measuring hose temperatures and even tyre temperature when setting up wheel camber on the track.
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Old 7th August 2009, 10:06
5exiAdam 5exiAdam is offline
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There is a VW Golf VR6 Radiator on ebay if you are interested. It is a big one with a double fan!

ebay number 130323080864
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Old 7th August 2009, 11:41
Gowles Gowles is offline
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Thanks Adam!
I'm currently in the process of fitting a new "standard" rad and sorting the squashed hose, new thermostat etc...
If the e-bay price doesn't go too silly, I'll try to get the VW rad to have a play with at some time in the future!

Best regards,
Simon
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