Buck62
Charleston, South Carolina
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jpancini,
The labor cost to pull your old engine will be fixed cost with either a rebuild or new engine. Then the decision is to rebuild the existing engine or a new engine. Personally, I would call the local Chevy dealer and price a new "crate" engine. The new engine will have the same warranty as a new engine. A total rebuid of your current engine will also result in a "brand" new engine but a proper rebuid will be a total tear down and include reboring the cylinders, reboring camshaft and crankshaft bores. Remilled and rebuilt cylinder heads, new oversized crankshaft, camshaft and pistons. This type of rebuild will be equal to a new engine. Good Luck
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rgatijnet1
Florida
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jpancini wrote:West Coast FT,
I live in the Indianapolis, Indiana area. I don't mind purchasing an engine from the internet if there is a reputable re-manufacture out there. I did have a mechanic do a compression check and #5 piston had no compression and #7 had some compression. The remainder of the pistons were ok. I plan on keeping this motorhome and I don't want more problems down the road. I'm not sure rebuilding the old engine will last 6 or 7 more years? Any advice is appreciated.
Thanks
Zero compression is a little strange. Low yes, but zero, I doubt it. Have a mechanic do a differential compression test. This is where air is pumped into each cylinder and you can actually hear where the air is leaking out. Air out the exhaust and you have a bad exhaust valve. Out the intake and you have a bad intake valve. Out the crankcase vent and you may have bad rings, etc. You may only need a valve job or to have your heads rebuilt. I would be leaning towards a bad valve or two.
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PhilipB
MO
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I bought a reman from Jasper a few years back for my boat. Yes....water will freeze if left in over a Missouri winter. This was a GM 4.3. Mechanic said cost was just about the same as a rebuild and the reman had warranty.
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okgc
southern Michigan
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Quote:Zero compression is a little strange. Low yes, but zero, I doubt it. Have a mechanic do a differential compression test. This is where air is pumped into each cylinder and you can actually hear where the air is leaking out. Air out the exhaust and you have a bad exhaust valve. Out the intake and you have a bad intake valve. Out the crankcase vent and you may have bad rings, etc. You may only need a valve job or to have your heads rebuilt. I would be leaning towards a bad valve or two.
I agree with this, Excellent advice
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HpyKmpr1962
Western NY
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okgc wrote:Quote:Zero compression is a little strange. Low yes, but zero, I doubt it. Have a mechanic do a differential compression test. This is where air is pumped into each cylinder and you can actually hear where the air is leaking out. Air out the exhaust and you have a bad exhaust valve. Out the intake and you have a bad intake valve. Out the crankcase vent and you may have bad rings, etc. You may only need a valve job or to have your heads rebuilt. I would be leaning towards a bad valve or two.
I agree with this, Excellent advice
Or as simple (to me anyways, ex mechanic) as a blown head gasket between 2 cylinders. Won't leak coolant or blow smoke but compression would blow from one to the other. Interject air into #7 and listen to see if it comes out of #5 exhaust. May have to do a tear down to determine if an engine is really necessary.
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Stim
NE Florida
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Non-Carbureted engines will last much longer than those with a Carburetor because the computer manages the fuel much more efficiently and that causes a lot less wear.
5 and 7 cylinders are side by side so the head gasket theory is the most logical. If the engine has had good oil pressure then all you really need is a valve job and timing chain changed. Chains are usually good for 100,000 or less.
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jpancini
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Thanks for all of the info.. I'm rethinking my decision and plan on talking to my mechanic tomorrow about doing a rebuild of the current engine. I just finished a trip in early October from Indianapolis to Bar Harbor and back, that is when the problem started. Large amounts of oil was being blown into the breather which created a lot of white smoke. The mechanic said there was no sign of water in the oil. This engine has always been strong and solid - even on the trip back from Maine.
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sum1
So-Cal
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Does your mechanic think you've holed a piston? If not, then the top end suggestions by rgatijnet1 and others should be considered. You probably won't have to pull the engine if it's valves or head gasket. Unless of course you've been wanting to hotrod it and have been waiting for the right excuse! In that case, "I'm sorry Mrs. Pancini. Your husband's right - it's a gonner and it's gotta be rebuilt."
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Daveinet
il
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I purchased my 502 from http://www.crateenginedepot.com/store/nbspnbspBig-Blocks-C54.aspx. If I had to do it over, I would either order the ZZ502 and put a different cam in it, or just buy the Ramjet. The reason is that the ZZ502 has oval port heads, which will still flow decent at low RPM, but are faster burn heads than the HT502. The Ramjet just has enough torque over the full RPM band that it would do just fine. What you want to stay away from is the HO502 with rectangular port heads, as they will not do much in the low end.
The HT502 has peanut port heads, which are designed for low RPM torque, but they are an old design cast iron head. The ZZ an aluminum head and has a better chamber design that promotes a faster burn. Faster burn helps efficiency as well as discourages detonation. They can get away with higher compression because of the faster burn. So, the best of both worlds is the faster burn head, but put a high torque cam in it, such as the HT cam. You can custom order any configuration of these engines.
The RamJet is also a serious contender as well. With longer intake runners, it will help the low end torque. The biggest advantage of port injection is that it allows for longer intake runners, without the fuel falling out of the air at lower RPMs. That has always been the limit with TBI or a carb, is that if the runners are too long, the fuel falls out of the air, and puddles in the bottom of the manifold. So this limits the length of the runner which hurts the bottom end. Port injection will do better in the low and midrange because of the intake design.
As far as the choice of rebuilding your current engine, several things. Your current engine block is an older design. There have been several improvements to the 454 block over the years, most of which was incorporated into the GEN VI block. These design changes are why the 8.1L lasts as long as it does. The crate engines all incorporate these new design improvements, including the roller cam. Of course the other reason is the power of the 502 over a stock 454 is substantial. The old line of there is no replacement for displacement is very true. The ease of the engine to cruise towing my GC is phenomenal. I can hold 80 mph up a 6% grade. Makes it very easy to pass on 2 lane roads. Being able to pull out in traffic like you are a car is pretty nice too.
While you can custom order a chip for your current computer, setting yourself up for burning your own chips is not bad either. For around 300 bucks and a laptop, you can learn to burn your own chips. The information is well documented. You start with a stock chip and then just modify the program based on the data you read back from the computer. For the most part, you tell the computer how big the engine is and how much flow your injection system has and it figures out the rest. This gives you a good starting point. Then its just a matter of fine tunning based on how it runs.
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bill h
coastal reconquista
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I would not make a decision without pulling the heads first.
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