Engine overheating under load

[Clarkey]

So, it's an SR20DET and the issue is the temp goes up when you give it the beans. No problem at all idling.

This has to be a blocked radiator or a jammed thermostat right......
The rad should be ok, it's an enormous alloy one which seems fairly new.

I'd say it's more likely to be the stat, even though they usually stick in the open position. I think my first port of call will be to remove the stat and take it for a thrash to see if it helps.

What do you guys think? What is the best way to clean out the radiator?

Oh, already tried changing the rad cap, made no difference.

 

[InvaderGIR]

Closed stat should oveheat at idle too? My 328i did anyway and that was a stuck closed stat.

As for the radiator...stick a hose pipe in there, turn on the tap to give a strong flow, b'reet.

I'd suggest flushing the whole system too, above method but fully d/c the rad and put the hose into a coolant pipe (also with the stat out).

 

[sigma]

I'd check the temp gauge too, they're not the most reliable of things apparently.

 

[Clarkey]

yeah I wanted to plug in my conzult to confirm the dash gauge but unfortunately my laptop is broken :/

 

[MissChief]

Water pump maybe sticking?

 

[Lashout_UK]

Knackered temperature sender, fuelling fault, shot water pump or head gasket.

Does it still run OK?

 

[Clarkey]

Yeah runs fine otherwise, drive it gently and it will go all day without the needle moving.

Knackered temp sender is possible, will try to get the temp off the OBD to confirm, but the laptop is another problem altogether.
Fuelling fault also possible, the engine isn't original, it's a red top from a JDM S13 in a UK S14. Without using a wideband, how could I tell though? Likewise ignition timing could be an issue, will try to get a timing light on it.
Shot water pump I'd say unlikely but won't dismiss it, surely it would overheat all the time though?
Head gasket, there's no oil/water mixing, it doesn't spew its coolant out at all, it does sound a bit lazy when cranking though, as if the compression isn't too great.

 

[Abraxaz1]

Most likely water pump, is belt slipping when you load the engine? Or when was the pump last changed?
What state is the radiator in? Are the vanes overlly bent or abused?
Does the heaters work if not possible blockage or air lock.
Other than that could be blocked or partially blocked engine block water ways

 

[Clarkey]

Most likely water pump, is belt slipping when you load the engine? Or when was the pump last changed?

No slip, no idea when changed.

What state is the radiator in? Are the vanes overlly bent or abused?

Looks like new. Is also really huge given the modest output of the engine.

Does the heaters work if not possible blockage or air lock.

Yep, works lovely. Heater on max brings the temp down quite effectively when it goes up too.

Other than that could be blocked or partially blocked engine block water ways

 

[Nomisf]

I know this sounds daft, but have you checked there is enough coolant in it. When I had my S14a it got the common leak from the turbo pipe, and lost enough water that it ran normally, until under load all the remaining water tuned to steam and I had to baby it home!

Also, I would get your fuelling checked if the usual things don't work - as I am sure you know, you really don't want to be running lean with an SR20!

 

[Clarkey]

Pretty sure it isn't running lean, the tail pipe is black and soot on the bumper too.

While I'm on the topic, the car feels slow as crap, no faster than my 328i really. Running only 9psi and there seems to be a ton of lag. The turbo on it looks like brand new, spotless, and has some braided oil lines going to it. Obviously it's had some turbo work but we don't know what. Red top had a t25 standard instead of the t28 on the s14 ones right? Will try and find some markings on it, see what's going on.

 

[Simon]

Could be water pump.

If its been miss treated in past the oil feeds on the camshaft block up and kill the cams, when they were new we ran a S14 on a 100k mile oil drain. Im not sure on the milage but the drivers would complain it didnt rev past 4000rpm.

The cams had worn so much do to blocked oil feeds that the valves hardly opened

 

[andrewdodd13]

Yeah runs fine otherwise, drive it gently and it will go all day without the needle moving.

This is what happened to my Starlet just before I got rid of it, and it was the water pump. A few parts of the impeller had disintegrated / broken off, so if you kept your right foot under control there was no problem, but when thrashing it there was nowhere near the water flow you would expect.

 

[Nomisf]

Pretty sure it isn't running lean, the tail pipe is black and soot on the bumper too.

While I'm on the topic, the car feels slow as crap, no faster than my 328i really. Running only 9psi and there seems to be a ton of lag. The turbo on it looks like brand new, spotless, and has some braided oil lines going to it. Obviously it's had some turbo work but we don't know what. Red top had a t25 standard instead of the t28 on the s14 ones right? Will try and find some markings on it, see what's going on.

That seems to be the same symptoms that crop up every time an SR20 goes wrong, during my ownership the following things caused such a complaint:

+ Post AFM air leak
+ Lazy/Weak turbo actuator
+ Turbo -> Manifold Gasket
+ Head to manifold gasket
+ Bad block earth

Good luck!

I am not sure on the turbo specs, I would expect an SR to have at least a T28 - if you have trouble with the markings, stick up a picture. It sounds most likely that either your waste-gate is open/weak/stuck or you have an exhaust leak pre turbo.

 

[sigma]

..

 

[sigma]

Hmm new turbo and overheating?

Sounds to me like the original turbo lines cracked and it possibly overheated. Very common problem.

 

[GeX]

My guess would be the waterpump, it's just not shifting enough coolant round when the engine is underload.

 

[Clarkey]

Seems like the problem was just a crappy dash gauge. In actual fact the engine was running too cool unless thrashed. Bad thermostat you'd think. Correct, I opened the housing to find no stat in there.

I'll chuck the new one in in a min and hopefully all will be well.

On to the performance. Found one obvious mistake, the accel cable bracket is wrong and the throttle is only opening to about 3/4 or so. Easy enough to get that fixed.

Whereabouts are the ID numbers on the turbo? I will try to find out what the unit is. Hopefully it is a t28 unit s14 spec and not the original red top t25g. I've read that the t25g is meant to have a really quick spool, this one certainly does not. Hoping to get a bit more boost out of it but not sure what is safe, I hear 12psi is safe on a stock red top.
Car has the following mods on it that I know of.
Apex'i air filter
FMIC + Big alloy rad
Paddle clutch + short shifter
De-cat + big straight through exhaust system.

Oh, and do engine mounts fail on these? I noticed the engine seems to move around a bit just while tugging the inlet pipes off.

 

[jigger]

Ive got a Sunny GTI-R and that engine comes stock with a Garret TB2804. I think its some kind of hybrid TBH.

I have replaced the lower engine mounts on a few transverse sr20 engines so I would say they are heavy on the mountings.

Im not sure about the PSI rating from the turbo side, but in good condition the engine is good for 3-400 BHP.

 

[Zuma]

i bet thre previous owner removed the stat to 'cure' the overheating problem he thought he had. then sold it when that didn't work