Help me find a solution to my always overheating 535i turbo please

[dmh2907]

as the title says, I have an overheating problem with my turbo M30 535iM

please excuse my often lack of proper grammar, English is not my first language

before i start, i should say that i know how to bleed the M30 cooling system and i do read almost every known article/thread on that engine's cooling system and general operations
i also have 3 other m30 engined cars, and they dont have any problem at all (except when finding oil filters for them)

oh yea, almost forgot its an '89 M30B35

so it goes like this:
Episode 1:
- i've done my turbo conversion last year with the stock bottom end and stock head, that is 9:1 compression, MLS, holset hx35, #42 injectors, aem fuel pump, megasquirt, autolite volvo turbo plugs, original bmw water pump, engine has around 100k miles.
- for cooling its pretty much stock except for a custom 3 ply radiator, i run no thermostat on all my M30s because it would never open even though the engine is 3/4 temp (i have lots of unused brand new thermostat as a result).
- with this setup on any weather on any day and any traffic conditions (i should say the weather where i live goes up to 36-40 C on average with 85% humidity) the engine temp NEVER reaches above 85C, at cruising its usually around 75-79 which is the way i like it

so then due to a bad crank bearings i tore apart the engine and set to rebuild it.
Episode 2:
- i "upgraded" the engine with a M106 crank, piston, and rods with a B35 block and B35 head (7.5:1 compression), stock cam, ARP (i use stock studs before), reused the cometic MLS gasket, Holset HX40, #42 injectors, aem fuel pump, megasquirt, autolite volvo turbo plugs, new water pump, and adjustable fpr
- i went for a drive on the untuned engine and the temp reaches 92-98C rather quickly (10-15 minutes), 100-110 if idling for long time, which is odd and worrying
- i thought it was because of the untuned state, so i went for a dyno tune, i got a good tune and was making decent power, still low boost (0.8 bar) but okay for running-in the new engine
- after the dyno i went for a cruise and the temp still reaches up to 92-98C quickly, worse if idling, but for some reason if get it to boost it goes down to 80-85C (the fan coupling was working good)
- so i went and made an aluminum 4 ply radiator and custom shroud and changed to a new fan coupling (this new fan coupling does not engage at high engine temp, so i later switch to my old one), and still the same, although it got to 98C slower than it was before but it still reaches that high, if i let it idle and do nothing with the AC on even at night it will go to 110C
- i tried using coolant, water, re bleed over and over again, new expansion tank, new cap, i even use a Volvo turbo expansion tank and cap just to try, its still overheats
- i remove my bumper to allow more air to get into the radiator, it helps somewhat but if left at idle for ~15minutes it will overheat, even cruising at low speeds it will overheat
- i have replaced the aux fan for a new unit, it runs perfectly but still no help
- i run a water outlet from the back of the head a la B34 style, still the same

Current Situtation:
- i have a IR thermometer and took the readings today when the MS said the temp is at 95C, to confirm it the readings are 84C @ rad inlet, 78C @ rad outlet, 94C @ thermostat housing (which is where the temp sender is)
- im still running the volvo expansion tank and cap because of space restriction, i have a wasted spark coil pack on the firewall where the BMW exp tank was
- of all things i replaced i havent replaced the hoses which i think are fine because they are not soggy or collapsed, i dont know if this matters though
- i read that ignition advance has an effect on temp, but i tried fiddling with it to no avail, on 9:1 comp i run 16deg advance on idle, i now run 21deg on idle, with cruising off boost at 32deg adv

sooo thats the story, sorry fo long post but im out of ideas...

any thoughts or ideas for my problem?

[Smoky540i]

You need to talk with the guy that has the "redfive" car...

Sent from my XT1565 using Tapatalk

[demetk]

Why is your rad outlet temp greater than your inlet temp. I think It should be the other way around.

[dmh2907]

You need to talk with the guy that has the "redfive" car...

Sent from my XT1565 using Tapatalk

you're right! i think i will try to do that

Why is your rad outlet temp greater than your inlet temp. I think It should be the other way around.

my inlet temp is 84C and my outlet temp is about 78C

[dmh2907]

An update for anyone in the future that may have the same problem.

Turns out the problem was in part due to:
A. The water pump pulley is 140mm which is for cold weather, since im in the tropics the 130mm one is needed, i ended up making a custom 110mm pulley.
B. The spark timing on idle is too low for a 7.5:1 compression engine, i ended up setting the idle spark advance to 25 degrees on megasquirt

Problem solved!
Temperature never goes above 85deg C on heave traffic with AC which is nice


Sent from my iPhone using Tapatalk

[Flash799]

An update for anyone in the future that may have the same problem.

Turns out the problem was in part due to:
A. The water pump pulley is 140mm which is for cold weather, since im in the tropics the 130mm one is needed, i ended up making a custom 110mm pulley.
B. The spark timing on idle is too low for a 7.5:1 compression engine, i ended up setting the idle spark advance to 25 degrees on megasquirt

Problem solved!
Temperature never goes above 85deg C on heave traffic with AC which is nice


Sent from my iPhone using Tapatalk

thanks for sharing

[Neel]

Nice !