1998 Toyota 4Runner overheating and loss of power

GLENN WARREN

MEMBER
1998 TOYOTA 4RUNNER
6 CYL
4WD
MANUAL
80,000 MILES

I work in Zimbabwe with the U.S. Embassy so good car maintenance is difficult.
Several months ago, my car started overheating when I would drive about 80 to 100 miles continuously at moderate to high speeds (no overheating with city driving). A cracked cylinder head was diagnosed and the head was planed. I subsequently took one trip with no problems but speed did not exceed 60 mph.

On a recent trip two things happened. At speeds of over 60 mph, the oil light would at times come on. Simultaneously, I had a loss of power going up inclines or hills. At times the light would not go on and I seemed to have full power even going up hills. At one such period with full power I was driving for a sustained period of 75 mph and the car overheated.

The car uses diesel. After driving now, I think I can smell a faint fuel smell.

5 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Try replacing the thermostat-not it do the following below:

Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following: Thermostat, Pressure test the Rad. Cap, Clogged radiator, Fan clutch, Radiator electrical fan, collaspe hoses, water pump.

Also might consider bleeding the cooling system

Always bleed air from cooling system after replacing coolant. Set heater for maximum heat. Remove radiator cap. Loosen drain plug and remove drain bolt (if equipped) from engine block. Drain coolant reservoir. Fill coolant reservoir to MAX mark with 50/50 water-coolant mixture. Loosen bleed bolt and fill radiator up to base of filler neck. Close bleed bolt when coolant flows out without bubbles. Tighten bleed bolt. With radiator cap removed, start and operate engine to normal operating temperature. Add coolant if necessary and check for leaks.

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Tuesday, August 12th, 2008 AT 2:11 AM

GLENN WARREN

MEMBER
3 POSTS

Your reply addresses the overheating. What about the oil light and loss of power?

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Tuesday, August 12th, 2008 AT 3:13 AM

RASMATAZ

MECHANIC
75,992 POSTS

Oil light coming on means low or no oil pressure-do an oil pressure check with a mechanical gauge if normal-replace the oil pressure sending unit-abnormal could be the oil pump/engine bearings/pick-up tube disconnected/sludge

Loss of power: low engine compression/air filter/fuel filter/injectors/and injection unit etc-

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Tuesday, August 12th, 2008 AT 5:29 AM

GLENN WARREN

MEMBER
3 POSTS

Thanks. The oil light seems to come on when there's a loss of power. And it seems to come on at higher speeds. When it doesn't come on at higher speeds, there's no loss of power. So, could there be some kind of electrical problem--when the oil light comes on the flow of gas is not regulated like it should be?

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Tuesday, August 12th, 2008 AT 5:44 AM

RASMATAZ

MECHANIC
75,992 POSTS

Do you have a check engine light On when this happens.

Have you check the oil level?

At one such period with full power I was driving for a sustained period of 75 mph and the car overheated.

When the engine is overheating it will detonate and lose power.

Back to your concern I cannot precisely pinpoint where the problem is coming from. The oil light circuit is not tied in with the fuel delivery system. It sounds as though the computer is sensing the oil pressure and trying to shut the engine down. This is as far as I can take you-Please await for an other moderator.