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| | | Blown engine advice | Joined: Jun 2018 Posts: 3 stranger | OP stranger Joined: Jun 2018 Posts: 3 | Greetings all my name's Ken and this is not an ideal first post. I screwed up and severely overheated my engine and now it's time to pay the price.
I have 1990 Chevy G30 van with a 5.7 (60K on the odometer) which was overheated and is now running rough with some detonation/timing issues. I took it to 2 different shops to diagnose, one stated the timing chain was loose and needed replacing, and the other shop simply couldn't diagnose the problem. So I was about to pay the first shop to replace the timing chain for $800, but thought it prudent to do an engine oil analysis, and compression test first to see if it was worth it. The compression test was as follows; Driver side --- Passenger side 140 ---130 35 --- 50 30 --- 50 125 --- 130
I tripled checked the first 2 reading on the driver's side as I thought (hoped) the gauge broke, but the numbers repeated. So no need to do an oil analysis. I'm assuming I heated the engine enough to warp the heads. My instinct is to replace the entire engine, but since I'm traveling and my shop is 3000 miles East I'm scrambling. Local shops have quoted $3000 to $4500 just in labor. Additionally this engine apparently no longer grows on trees! The local chevy dealer says there're no more in stock, and while JEGS quoted me an ATK brand rebuild I found out today it's out of stock and they don't know when one will be available.
Options I'm pondering are unloading the van, or shipping it home, and just having the engine rebuilt locally once I remove it.
Another option I'm considering, which I'm hoping to get some opinions on, is just having the top end rebuilt. I figured I can remove the heads and have them rebuilt locally without having to remove the entire engine. Has anyone here done this? And also do you think the engine block surface that mates to the heads needs to be resurfaced due to the overheating? This option sort of feels like I'm rolling the dice (again!) and hoping nothing else, like damaged pistons/rings/cylinder walls, was damaged by the overheating.
Lastly (fingers crossed) is it possible a loose timing chain can cause low compression in some cylinders, but not others?
Thank you for any thoughts on this, Ken | | | Re: Blown engine advice | Joined: Aug 2001 Posts: 12,107 Likes: 37 Maniac | Maniac Joined: Aug 2001 Posts: 12,107 Likes: 37 | Well, when a motor overheats badly you can score the cylinder walls and cause a loss of compression, crack the valves, crack the heads, warp the heads, and warp the block. The first thing I would do is a leakdown test to see if you can pinpoint where you are losing compression.
A loose timing chain would cause low compression in all cylinders. It is possible you wiped out some lobes on the cam.
If the heads warped, then the block deck likey also warped and would need to be cleaned up.
Lousy situation, sorry to hear you are in it. Good luck!
Hey, maybe post where you are at and someone local can help you out.
Windows- they're what make a van worth owning! | | | Re: Blown engine advice | Joined: Sep 2005 Posts: 9,855 Likes: 234 carpal tunnel | carpal tunnel Joined: Sep 2005 Posts: 9,855 Likes: 234 | 1.) Are you able to do a cylinder leakage test? Compression tests are almost useless (IMO ), it'll tell you there is a problem (which you already know) but don't help much to diagnose. A leakage test will show you where the pressure is escaping, if there is a head gasket/cracked head or a bent valve or a scored cylinder,etc so that you can make a more informed decision. If it turns out to be cracked heads/gaskets (for instance), a new set of heads/gaskets to get home now and a new short block later would be a more wise use of resources. If the "bad" cylinders show low/normal leakage (again for instance) then you wiped the cam lobes. But you'll need more info....... a leakage test by someone who is competent will speak volumes. My 2%
Last edited by CatFish; June 04th 2018 9:20 pm. Reason: kant spel
| | | Re: Blown engine advice | Joined: Jun 2010 Posts: 18,286 Likes: 558 | Joined: Jun 2010 Posts: 18,286 Likes: 558 | Welcome to the site Ken ....
SUNSHINE VANS-VAN DIEGO ADRENALIN BY THE GALLON & CHASIN RACIN ONE FOR THE DIRT & ONE FOR THE STREETS '93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB '92 CHEVY G30 454 BEAUVILLE EXT 146" WB | | | Re: Blown engine advice | Joined: Mar 2016 Posts: 339 enthusiast | enthusiast Joined: Mar 2016 Posts: 339 | Those numbers tell me that the head gasket is blown between the 2nd & 3rd cylinder on each bank.
Tucson-it's a dry heat...like an oven
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