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I have a 1990 Isuzu Trooper. It started running really ...

Sent to Car Experts July 02 07:36 PM

I have a 1990 Isuzu Trooper. It started running really rough. I took it to a mechanic and they told me that I need a new head gasket. The compression on the front two cylinders is around 145-155. The rear two are at about 75. I was given an estimate of about $1000.00 for repair. Is this reasonable? The truck has 150K miles...is it worth it? The truck is in very good condition otherwise.

 

Optional Information:
1990 Isuzu Trooper

Customer (name blocked for privacy)
Status:  Closed   Value: $10
Answer
July 2 7:53 PM (16 minutes and 42 seconds later)
         
REPLIEDCheck Mark

Hello.

Low compression can be caused by a number of reasons. Yes a blown head gasket would be one of them.

Other causes are the piston rings, bent/burned valves, worn cam shafts, bent rods, or even an excessive amount of fuel in the cylinders. You see, the gasoline washes off the oil off the cylinder walls and the rings lose compression.

However, if your technician has narrowed it down to the head gasket... A thousand dollars is a quite reasonable for the job. If the job gets done right. That means, remove engine components, remove the cylinder head (the complete top half of the engine).

Now, the head needs to be sent out to the machine shop. This is where it is pressure tested, cleaned, new valve seals are installed, and the head's mating surface is machined smooth and straight.

The technician needs to clean ALL part mating surfaces to a spotless shine. Also, all the parts should be cleaned nicely.

The cylinder head is then reinstalled, torqued in a precise manner, all components are reassembled, the fluids are refilled and the test run. A follow up appointment is good business practice.

Also, parts... Head gasket kit (all gaskets needed) head bolts, cleaners, materials, fluids, filters, plugs, thermostat....

Is the truck worth it? Only you can say that. What's the condition of the vehicle? Tires? Brakes? Interior? Exterior? on and on...

If you have any further questions... let me know.

 

rmldaytona -- ASE technician -- 99% Positive Feedback on 508 Car Accepts
ASE Certified. Aerospace engineering studies. Drivebility.
Reply
July 2 8:16 PM (23 minutes and 7 seconds later)
         
Reply to rmldaytona's Post: Overall, the vehicle is in good condition. No rust, less than 10K on the tires, 4WD works well. My hesitation is with the 150K on the motor. Is that a lot for a trooper?

It seems to me that one of the most obvious diagnosis (not sure if it was narrowed down or not)would be a blown head gasket. The others that you mention would only be found after/during the removal of upper engine. The motor has had a little bit of lifter noise (slight ticking) for a few years but the noise seems very minor.

When you gave the list of things for a job to be done right, is this standard procedure ( I am dealing with Midas)? Initially, I thought I had a manifold leak (and do) but it seems to run a lot deeper than that.
Customer (name blocked for privacy)
Answer
July 2 8:49 PM (33 minutes and 14 seconds later)
         
ACCEPTEDCheck Mark

150k is a good amount of miles on any engine. It's nearing the end of its life.

No, you can narrow down further problems by testing. Perform a cylinder leak down test to see where the air out of the cylinder is escaping. This is done by pressurizing the cylinders using compressed air.

If it is going into the cooling system, then yes, you likely have a blown head gasket. Also, checking the cooling system of combustion gases is a good clue.

If the air goes into the intake or exhaust, then you have a bad valve.

If the air escapes into the crank case, then you have a piston ring or fuel washed cylinder walls.

All the thing mentioned in the repair are standard procedure for a good, lasting repair.

Feel free to let me know if you need further assistance.

 

 

 

rmldaytona -- ASE technician -- 99% Positive Feedback on 508 Car Accepts
ASE Certified. Aerospace engineering studies. Drivebility.
Reply
July 2 8:58 PM (8 minutes and 16 seconds later)
         
Reply to rmldaytona's Post: Thank you!
Customer (name blocked for privacy)
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