Please help diagnose oil leak

My 93 trooper has oil leak, I know and think it was minor until I had a shop work on it. Before the work, the botom of the enginewas messy but no oil drips to th ground. Then one day I asked for a good garage
to a friend, and he told me the shop. I did not fully believe it and asked to a co-worker, who also think that was a good shop. "They never fail me",that's he said. So I havee the shop check the truck and they said it needed a new valve cover gasket. I have them done it, but after two days I saw worse leak. Oil drips to the ground where I parked. I also noticed vapor smelling oil when I waiting at traffic lights. I have them run a check a again, they said it was leaking from thr oil pan and the valve cover was ok. This time I did not believe them because I saw oil all around the starter, which is higher than the oil pan. They then blame the rear main seal. Is there a way to diagnose whether the oil is from the rear main or the rear valve cover gasket?
Thanks
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PC Player wrote

while it is not an answer to your post, in case it helps, I've gone through a few 93 troopers with precise same issue
one common thread was a tech service bulletin (TSB) issue by isuzu around 94 or 95 which called for the installation of some plates (4) to prevent some bearing or crankshaft (?) issue
each 93 trooper that had that service done, developed an oil leak, with the vapor smell while idling or when just parked that you describe
I was told by two service techs at two isuzu dealerships when I took one particular trooper back to diagnose the leak (within 1 month of the TSB installation) - that they had accidentally cracked or tightened something that caused the leak but that I would never be able to prove it
perhaps you will discover the true source, all I can tell you is that this is a common item but (here's the exception), I have also had two 93 troopers without the TSB performed and they do not leak
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Thanks for your help. I called two dealers and gave the VIN number to check whether or not the recall work had been done. Both of them said same thing: there was no recall on it. So I think the work has not been done.
I had Midas checked the leak, they said the valve cover and oil pan were both leaking but the rear main seal is not visible. Is it possible that fixing the leaking valve cover will make the rear main seal leak much worse?
snipped-for-privacy@mailinator.com (Joe Isuzu) wrote in message

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PC Player wrote:

I wouldn't think so. The only thing I can imagine doing that would be more crankcase pressure. Valve cover leaks are usually just due to a bad gasket seal.
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How could I prove that they did not do their job right? It is a costly work, they will try their best to blame something else instead of working on again for free. Just as I said, I had them check the valve cover, they said it is not leaking and blamed the oil pan. I just pointed out that was not true since the part on top of oil pan also got a lot of oil.
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I can tell you exactly what your oil leak is. On the back of the cylinder head there is plug, sort of like a freeze plug, but it actually caps off the cam bore. Because the cylinder head is made of aluminum, the thermal expansion is much greater than that of the plug. This differential expansion between the plug and the head will cause the plug to come loose from the cam bore and leak oil profusely. It can look like a rear main leak or a cam cover gasket leak. The smell you are experiencing is the oil dripping on the exhaust manifold. There is actually a recall from Isuzu to install some plates on the back of the cylinder heads to retain the plugs in the cam bores. BUT, you'll not get any satisfaction from Isuzu of North America. I was told that the work had been performed on my Trooper, but it definitely had not. Since their records showed it had been done, they were not going to do anything to help! When I talked to the service folks at the Isuzu dealer, they said that the cylinder head had to be removed to fix the leak. I figured out a way to fix it in situ. I fabricated my own plug retention plate from 1/4" aluminum. If you are still having a problem and want more details, please contact me directly and I can explain the repair in detail.
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I can tell you exactly what your oil leak is. On the back of the cylinder head there is plug, sort of like a freeze plug, but it actually caps off the cam bore. Because the cylinder head is made of aluminum, the thermal expansion is much greater than that of the plug. This differential expansion between the plug and the head will cause the plug to come loose from the cam bore and leak oil profusely. It can look like a rear main leak or a cam cover gasket leak. The smell you are experiencing is the oil dripping on the exhaust manifold. There is actually a recall from Isuzu to install some plates on the back of the cylinder heads to retain the plugs in the cam bores. BUT, you'll not get any satisfaction from Isuzu of North America. I was told that the work had been performed on my Trooper, but it definitely had not. Since their records showed it had been done, they were not going to do anything to help! When I talked to the service folks at the Isuzu dealer, they said that the cylinder head had to be removed to fix the leak. I figured out a way to fix it in situ. I fabricated my own plug retention plate from 1/4" aluminum. If you are still having a problem and want more details, please contact me directly and I can explain the repair in detail.
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Hi, Please send the info to snipped-for-privacy@yahoo.com
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