what size external oil cooler do i need

[six]

hi all

I have a 2027cc - 90.5x78.8 c35 cam in my vw panel. Its only just run in, and just finding out it runs hot.

130 deg c at 65 @3500 rpm(ish) !

So fitting a external oil cooler seems the way to go. What size cooler do i need? I see lots of people run mocal ones should i go for the 235mm x 13 row? 16row or bigger?

Also what pipe should i run? i have reinforced rubber pipe for the full flow oil filter atm should i look to go for braided to help keep up oil pressure?

any advice greatly appreciated

 

[kev mc]

ive just ordered an atomic cool this http://www.cbperformance.com/catalog.asp?ProductID=1331" onclick="window.open(this.href);return false;
from beetleragtop on vzi. nice cooler nice price. as for oil lines, i would get all the bits like filter head, thermostat and cooler and then go to a hydrolic comercial works and get them to make the lines up for you. they will be top quality and will probably be cheaper than the steel braided hose you get at the motor factors.

 

[six]

chaps over at vzi are saying its actually an over heating issue so gotta verifiy that first i think.chances of holiday this yr is quickly going down the pan again. grr

 

[Trikky2]

chaps over at vzi are saying its actually an over heating issue so gotta verifiy that first i think.chances of holiday this yr is quickly going down the pan again. grr

Yes, assuming of course that your temperature gauge is reading accurately, your overheating.

The stock cooler should be able to cope.

Adding an extra cooler will cool only the oil - not the whole engine and its in the cylinder heads you get the most heat and where the damage gets done. Hence why fitting an extra oil cooler is often treating the symptom and not the cause.

I would first check your gauge is accurate - not just at 100C but also at 70C ish and 110C ish if you can manage it. Reason I suggest this is because I have come across a couple gauges that read ok at around a 100 but then went miles out either side - presumably due to faulty or wrong sender units.

If the gauge turns out to be accurate then find the cause of the overheating.

Start with the basics, all tinware and seals in place, timing, valve clearances, thermostat and flaps present and working, little rectangular bits of tinware between the cylinder barrels and pushrod tubes correctly in place etc.

You dont say what fuel system your using. Whatever it is, carbs or injection, you need to check its not running too lean since this will cause overheating. Check the mixture by looking at the plug colour. Incorrect jetting for instance may give you the correct mixture at tickover but lean out under load at higher rpm.

What exhaust are you using? Stock will strangle the larger engineyou have as will a small flange 4 into one for instance.

 

[six]

Hi

checked the tins, a few gaps just joins, nothing major, there is one hole size of a 50p, im sure this dont help so will fill it up, but i ran the old 1600 without the front tin over gearbox harder without this kinda problem.

timing is 28.5 deg, valves done and checked as are points and plug gapped to 0.8mm everything else looks ok. the lil square bits of tin are definitly not there. was built by airspeed who said they are not needed. So i provided them and requested them.. long story but they binned them along with the hoover bit, ive fitted another hoover bit, but havent taken heads off to fit the others. Im not running thermostat, but the flaps are installed and fixed open.

Im running dells 36, 30 vents 60 idle 122 main not sure of airs think 180. 55 pump i think. fule pump is mechanical. Im dashing home at lunch drop in a fuel pressure gauge and measure that.

its just completed its first 500 miles. plugs came out after the last 250 miles a reddish brown colour, engine never went above 2500 rpm. i belive this is still on the idle circuit if not just on the mains

im using a speed shop big bore, 1.5 inch with a a turbo muff on the end. certainly enough i think!

i think your right, its sounding fuel related. either pressure is too low, ive checked the float levels open and shut, they are ok, or the mains are too small. ive ordered some 125s and 128 mains to swap out.

thanks

 

[Trikky2]

Ok sounds like your sorting it. Reddish colour on the plugs certainly suggests theres issues re hot running and maybe associated detonation.

Whichever person building your engine told you the plates under the cylinders were not required is not competent and should not be allowed or trusted to build engines without further training.

These small bits of tinware are Vital in ensuring enough cooling air goes to the cylinder heads.

Without them in place an excessive amount of cooling air spills out between the barrels instead of being forced through the cooling fins. Sorry to hear you had to deal with such retards.

 

[six]

whats the detonation about then? same as pinking? i was told, that reddish colour was ok, this is just an additive in petrol.

plenty of info on airspeed on here and other forums. just a shame I found out too late.

cheers

 

[six]

ok just checked fuel pressure, 2.5 at idle but as revs increase pressure decreases, getting about 1psi at 3500 rpm!

starvation issue?

 

[Trikky2]

Yes detonation is the same as pinking and will occur on overheating engines.

Its concievable the red colour is coming from a fuel additive I suppose - I know that for a while the fuel in France used to leave reddish deposits wherever it seeped, like around throttle spindles, though I have not seen this in a fair few years. Plugs should normally be grey on the electrode going to black on the body.

Re the pressure, if there is still 1 psi it means there is still more fuel being supplied than the carbs are actually using. If they were using everything the pump has then pressure would drop to zero surely?

Such a pressure test is not really going to tell you much since without a rolling road you cannot check the supply is sufficient since the engine has to be under a lot of load to be using the max amount of fuel. I dont suspect insufficient fuel delivery though because if it were the problem you would suffer severe misfiring under load - like when going up a long hill.

 

[six]

i took the test from here http://www.vw-resource.com/fuel_pump.html#pressure there was pinking at high load but i thought that was sorted. i could be that its still there i just need to find a more constant test route.

is it possible I mistook the pinking for det and actually the low pressure is the problem. correct me if i way off just getting my thoughts on to paper as it were

 

[six]

a few pics (we all love the pics! )

this one is the residual pressure. one engine is off didnt go down for 10 mins. This is the lowest pressure recoreded at 3500 rpm

and zero after i let out pressure

Engine Bay. note no heater oulets, on fan housing. the holes have been welded and replife holes cut inside the housing

the only hole in the tinware, ill cover this up tonight with a plate

thanks

 

[dubdubz]

where are you in the uk? I have a lc-1 so can see what the afr is during real conditions - welcome to use it if it helps stop you killing your engine.

You do need the under cyl tins as Trikky says, but I have seen engines without them running fine.

It does sound carb related to me [ I had similar issues until I got my carbs dialled in with the lc-1 ]

 

[six]

wow thats very kind to offer. I am in Bournemouth thought bit far thanks though

 

[dubdubz]

I have been thinking of renting it out, fairly low cost say £15 a week excluding postage, only snag is if it either got lost in the post or broken I guess....

I need to do some tuning today /sunday , but could send it next week, although I haven't made an exhaust clamp as yet...I welded a lambda bung in my exhaust so it's in all the time.....

 

[six]

how much does one cost? i'd gladly rent it from you. would a clamp on the exit after the silencer be ok? could do insured delivery and i could send a cheque or something for full amount just in case something happens to it in my care?

 

[dubdubz]

theres one on ebay now 50.... mine was 150 new I think? the major draw back is no rpm logging....you kind of have to manually log that ie drive at a constant 3000rpm in 3rd, and watch the afr meter on the lap top......

 

[six]

update. Done a 200 mile drive last night all un eventful hot running is sorted, it was the fuel pump.

while i was at it though i also put an equal t in the fuel line rather than daisy chained the two dell carbs together.

Im getting 3.5 psi at both carbs now

i still need a cooler i belive. it runs at about 105-10 deg c at 65mph now but long run at 70-80 its gets hot i chickened out of 82 @ just under 120deg c after a 5 mile run.

a 13 row cooler will be good i think. in the mean time.. 65 is great, i never intended going much faster but knowing its capable and could do a run to the ferry might be worth knowing

Thanks for all your helps, dubdubz, still putting on lc-1 for better tuning, getting the boss welded on today

 

[Trikky2]

Glad to hear you feel its sorted now.

I have to admit I am a little puzzled though.

Normally if a fuel pump delivers insufficient fuel the carbs will run out completely when under load like going up a long hill for instance. eg. the vehicle will misfire more and more until it comes to a stop since it has run out of fuel. Odd.

How many miles has your new engine done? Reason I ask is because new engines often tend to run hot as they bed in, gradually running cooler and cooler over the first 2000 miles.

Lastly, have you now fitted the small metal plates that fit between the barrels and push rods? If they are not fitted it will cause overheating on the heads and no amount of oil cooling will cool the heads.

When the heads overheat there are hot spots that start to glow and these glowing bits will ignite the fuel mixture before the spark plug does giving you the effect of massively over advanced ignition timing which you will hear as pinking. Left to run like this the heat can rapidly build and cause valve failure.

Sorry to keep on at you but I have seen too many engines fail for silly reasons - just trying to save you a heap of money/trouble later

 

[six]

its got 768 on there now.

its definitely a million times better , yeah i dont fully get it as i'd expect the same as you with that. I dont think therefore the bowls went dry just super lean, i think t'ing the pipe rather than a daisy chain has helped too, making sure 1/2 dont go lean.

i recalibrated my oil temp sensor out of paranoia, that was out also by 5-10 degrees (i put a new sump plate on there, better earth or something)

I haven't done the cyl tins yet, after finding so many issues, bodges and dam right poor workmanship, ill be tearing the engine down after the summer anyhow. Ill go steady until then, Ill hope its ok.

Id prefer to understand how its fixed like you, but hey its working.. next stop france cant wait

thanks

 

[dubdubz]

six,

make sure you get the lc-1 up and running, I could send you some info from Jon aircooled .net guy, it's all about the egt, not all but a lot...and oddly lean doesn't always mean hot...it took me ages to get my head around it, but my engine cruises around 16:1 afr, and runs at around 90 [uncalibrated]

when I set my idle at 14.7 afr , or stoic? this was giving me a warm engine, lowering the AFR - leaning it out lowered the temps considerably.

make a cuppa and skim through this
http://www.thesamba.com/vw/forum/viewtopic.php?t=293837&postdays=0&postorder=asc&start=440" onclick="window.open(this.href);return false;