4d56 overheating w/ A/C on on traffic

[miked]

Symptom: overheating (>212F & <220F) with the A/C operating on traffic
Engine: 4D56 turbo
Trans: A/T internally cooled by engine radiator

Previous R&M done:
1. Head Gasket replacement (5 months ago)
2. Installed 82C thermostat (last feb 2011)
3. Changed to SAE 15W-40 engine oil (2 weeks ago)
4. Valve clearance adjustment (0.25 mm) 2 weeks ago also

Other inspected parts:
1. Coolant level ok. No leaks and doesn't consume coolant. I usually recycle the coolant at the reservoir back to radiator. For the past 5 months, I approximately consumed 1.5 liters of water.
2. Upper hose not hard as a rock
3. Lower hose not soft as a sponge
4. V-belt tension ok
5. Water pump not weeping coolant via weep hole. water also circulates as per inspection at the rad neck
6. No binding brakes
7. No cross-contamination of engine oil, coolant and AT fluid
8. Bubbles about half an inch to 1 inch come out of the rad neck in intervals of about 5 seconds or more even at operating temp. Coolant level rises up at rad neck
9. Exhaust smoke colorless at idle
10. Cools down after constant high revs at idle, highway runs, or with the hood open and sometimes after splashing water at the A/C condenser (note: not the engine radiator)
11. With the hood closed, temp climbs =>212F with the A/C on but stays in between 180F & 200F with the hood open.

My gut tells me that its an airflow problem and the headbolts coming loose again. I just did the head gasket job 5,000 km ago.

Please help guys. thanks

[miked]

Before i installed the thermostat, it overcools on highways and overheats on traffic.

Now it is thermostat equiped it stays at 180F before open driving then stays between 180F & 200F on open driving. the problem starts on traffic. with the aircon on, it rises faster. with the aircon off, it doesnt rise that much. both situation with hood closed. i have this feeling that tells me an airflow problem.

[rmpmla]

sir, have you check the radiator clutch fan?

baka kailangan ng silicon oil refill.

[reym]

Hi SIr Miked,

Have you checked if your head is warp free?

[Dieseldude]

Look at the temp setting of thermostat. Opening temp is normally stamped on the thermostat. It will open at that setting.

[utk505]

Check fan clutch , if ok , remove radiator clean radiator fin and also the condenser fins if still overhears may problem sa engine

[marz]

sir, have you check the radiator clutch fan?

baka kailangan ng silicon oil refill.

+1 ako dito, malamang yan ang solution sa problem mo.

[miked]

sir, have you check the radiator clutch fan?

baka kailangan ng silicon oil refill.

i refilled it about 6 months ago i think. doesn't free wheel when engine stopped....if ever the silicon content is good. i'm thinking na yung bimetallic strip ang may defect.

Hi SIr Miked,

Have you checked if your head is warp free?

as per inspection las head gasket change, the head is still good.

Look at the temp setting of thermostat. Opening temp is normally stamped on the thermostat. It will open at that setting.

82C as indicated on my first post.

A very simple Tstat modification you can do is to drill it. We do it on a lot of the higher performance cars here in the states, lowers the temps of your car without loosing the function. Sometimes you can't get a stat with the range you want so you can just drill it.

This is particulary common on 180F ones. I have put in a drilled stat on every Grand Prix I have owned including the Daytona 500 one I have now (they are superchared from the factory) It gets to 110F here in south Texas so you need it. Most of the Corvette and Z28 guys do the same thing as well.

Two 1/16" holes should make a nice difference for you and might eliminate your problem. I run a drilled 165F stat in my car. I drilled out the one on my Elgrand as well. It had no stat when I got it which I don't like so I replaced it. Never gets overheated no matter how I pound on it.

been thinking this one. read it from a motor mag but what part of the tstat should be drilled with respect to the bridge?....


road trip kami kahapon here sa province. from 1130-230, even on highway with the A/C on, the temp climbs to 212 and higher. pero when i put off the A/C, bumababa na.

then 3pm onwards stayed at 200F and sometimes lower with A/C on pa rin.

yun nga lang pagdating sa bahay, iniwan ko na naka on ang A/C while letting the engine cool off with the hood closed- ayun umakyat uli sa 212F. i switched off A/C and opened hood and some high rpm ayun bumaba naman...something like a cyclic overheating is happening and i don't know why..take note halos high revs ang ginawa ko just to test my hypothesis......

can't afford to sacrifice the comfort of having an A/C esp summer with my kid on the road.

i'll tinker with it this weekend. buti na lang dinala ko tool set ko.

[phezthie]

hey bro, yung a/c ba na check mo na kung hindi nag hi-high pressure?... pwede din kasi iyon ang cause...pag high pressure, mas mahirapan fan mo palamigin yung rad and condenser..

[miked]

plus another culprit is the A/T could be overheating also contributing to the cyclic reading on the gage. my plan is to put an external cooler and bypass the internal cooler...hirap nga lang maghanap lalu na andito nako province for a vacation.