~ Anno Domini

Guys, I am at a crossroads wondering if I should keep my 1989 Corvette six-speed. I have had it for 20 years. I had the engine rebuilt in 2010 and the job wasn't done quite right and it's burned excessive oil ever since then, but the car runs well. Today I am at a point that once a year (in the summer time) the car begins to stumble and I replace all the spark plugs and the car drives great again, strong, fast. The problem is that #7 spark plug gets fouled up with oil and #4 is a bit fouled too, but not as bad. The other plugs look normal. So I just replace them all until the next year and the car has been running fine and I don't mind changing the plugs. Here is the NEW problem. Now the car needs a new head gasket. There is no coolant in the oil. The oil is normal, and the car is not overheating, but there are bubbles in the radiator it seems pretty clear that there is exhuast gases getting into the coolant. Here's my question. I can't afford to rebuild the engine, but would spend $2500 ($1900 US) to replace the head gasket. I don't mind changing the plugs once a year. If the mechanic knows all this and we just replace the head gasket to patch it up do you think this can increase the oil burning. Will tightening of the head gasket, etc, make my engine oil burining even worse ? Your opinions are of high value to me. Thank you.

pologreen1

How much oil are you using?

Leaking or being burned as in, you see blue smoke out the exhaust? I feel like you are looking in the wrong direction.

If you truly are broke and can't fix it now, my advice is to try the thing most are afraid of... a goopy oil additive and run it. I just sold a jeep and told the buyer I ran it for YEARS it stopped using oil and ran for me for 100k and now this guy's daughter drives it all over.

it is an SBC no big deal, and the head should not be impacted oil consumption, my guess is time for a short block refresh etc. In the mean time dump junk in and go. What is the worst that can happen? You already possibly need motor work.

Again, use at your own risk, but people warned me against cheap radiator fixes and oil additives and I NEVER had a problem, although that was a daily driver beater it still was just a 318 and kept the thing going since I put both in in 2005.

~ Anno Domini

Hi Pologreen, I don't have blue smoke out of the exhaust, but the engine burns more oil than it should. I have not kept track of it, but I probably add 1 or 2 litres of oil between oil changes (5000 kms aka 3000 miles). Once a year #7 spark plug is caked with oil and #4 is a bit caked too, but I change the plugs and the car runs great again for another year. Honestly, it does not bother me to change the plugs once a year. My problem is exhaust gas is getting into the coolant so it looks like it needs a head gasket. I'm wondering if I just change the head gasket (because I don't want to spend money again to rebuild the engine again, I already had it done in 2010). So if I just change the head gasket and fix the coolant leak is it possible to go back to status quo and just replace the plugs on a yearly basis OR could replacing the head gasket increase oil burning ? I'm at a point where I don't want to spend money to rebuild the engine having done it once already.

jv9999

You need to do compression and leak down tests. You may have worn guides or just bad valve seals. IMO, you need to learn how to work on it or it's just going to drive you into the poor house. Old cars, especially old vettes, get real spendy fast if you're paying someone else to do everything.

C6_Racer_X

"Just replace the head gasket" might turn out to be more involved than you think.

Usually they don't leak unless the head has warped or has other issues. On the plus side, while getting it checked at the machine shop, they can also check the common points for oil leaks (valve stem seals especially). A "head gasket set" will usually include new valve stem seals.

There's no way I'd go to the trouble to pull the heads and not have them checked out and refreshed by a machine shop. It's not worth the work and the risk of still having a leaky head gasket, or worse problems, after replacing just the gaskets.

~ Anno Domini

Thank you all for the input. I agree jv9999, fixing the car yourself can really save money. I can do basic things, but when it comes to internal engine problems that's when I have to get the mechanic shop to do it, unfortunately. I am really uncertain what to do. I have one shop that says they would replace the head gasket for $2500 Canadian ($1900 US). That includes resurfacing the heads, but that is not fixing the oil burning problem. As I said on post #3, it would not bother me if they fix the coolant leak with a new head gasket because I don't mind changing the plugs once a year. Another option is just keep driving the car like it is right now and keep topping up the radiator. It drives nice and does not overheat. I will be praying about what to do, just don't want to spend 6 thousand to rebuild this engine again..

hcbph

Have you considered a crate engine? I've seen where more than one person has said it was more cost effective for them. If you don't need a core, you could still have your original block in case you ever want to fix it and go back to numbers matching.

Just a thought.

rjacobs

Holy rape job...

You're talking like 50 bucks in gaskets(the entire upper end gasket kit is only $150) and $75 for a set of head bolts(you shouldnt reuse factory TTY bolts). Also throw in say another 75 bucks for oil and coolant. So say $225 for parts. You say that price includes resurfacing them, which is maybe $100 at a machine shop. So $325 in parts and machine work... 1575 in labor... just seems CRAZY expensive to me for a basic head gasket job.

MaineJim

I'll second the idea of replacing the motor with a crate one.For 2.5k or less you can buy a brand new motor.

~ Anno Domini

I have read everyone's comments and appreciate your input more than you know. As you guys know, we love our corvettes. I mean, it's not an idol, but we do like our cars and I've had mine for 20 YEARS and it is almost like wearing a glove you get so used to it. Honestly, I don't know what I'm going to do. I will probably be on the phone today making calls to different mechanics. I will mention a crate engine, but as mentioned I spent 6,000 dollars in 2010 to rebuild the motor and really don't want to do it again. I wonder if the money would be better spent on another car OR is there a way to fix this at a reasonable cost and keep it running for more years. Well, I'm a Christian and will be praying on what to do, but this is a tough call. Last summer I put new tires on it, had the bose amps repaired, etc, and even with the problems I mention in post #3 the car is running great. 20 years. Sigh. More later as I gather information. Thank you all.

Churchkey

Don't think you have serious oil consumption issues when I was employed as a dealer tech one quart of oil consumed in 800 miles was considered normal for a new vehicle.

Suggest anti fouler spark plug adaptors or just change those 2 plugs a couple of times a year.

To check head gasket issues: If it is not loosing or puking coolant you probably do not have an issue.
Or:
Radiator cap off idle the engine until the thermostat opens then pinch the coolant recovery hose & place a condom over the radiator fill if the condom balloons combustion is entering the cooling system. Before dropping thousands on a mechanical repair try this copper sealer it works.
https://shop.advanceautoparts.com/p/...FVDbwAod1MAAGw

Good luck

C6_Racer_X

I would get the estimate broken down parts (full list of parts), sublet work (machine shop), and labor. Your estimate seems high to me, but it could just be different markets.

Any machine shop that resurfaces heads should pressure test the things first to make sure there are no leaks (cracks), and that the valves are seating properly. On an engine this old, in addition to resurfacing ($100-$150 or so for both heads), you'll almost certainly need a "valve job" (grinding/resurfacing the valve seats) at a minimum. That will add $75 or so to the machine shop charges to do both heads. If any of the valves or valve seats are damaged, that will add even more. You won't know that until the machine shop gets the heads and inspects them thoroughly. Expect the total from the machine shop to be $400 (US) +/- $200 depending on the condition of the heads.

The shop should be using a full "head gasket/upper gasket set." That set will include new valve stem seals which should be sent with the head to the machine shop.

If the heads are properly serviced, it will most likely resolve the oil issues fouling the plugs. There are a lot more places for oil to leak into the cylinders in the heads and head gasket than in the block and pistons (rings).

If you don't care too much about this engine and want to save money, that leak stop stuff that @Churchkey linked to isn't bad to buy some additional time. I've used that before on an engine that I didn't care about that had a head gasket failure right before I was planning a long trip. I followed the instructions on it exactly, and that stuff lasted until I sold the car a few years later. I did disclose to the buyer that I had used a leak sealant to "repair" a head gasket leak. The stuff does work. No telling whether it will clog up the heater core or cause any other issues, but if you follow the instructions exactly, it will usually seal a leaking head gasket.

fredk

I agree with jy9999 get those tests done. Replacing heads after you get them checked or rebuilt is not a bad job. Just make sure you take lots of pictures, I did it.

John A. Marker

I would suggest getting a compression test for all the cylinders. They should be within 10 pounds of each other. If your compression is good they I would look at the intake manifold gaskets as the problem with the oil consumption. Small block Chevy's have been know to have a issue for years with the intake gaskets leaking on #7 and #8 and sucking oil from the valley. When Chevy upgraded to aluminum heads a new issue cropped up. Blown head gaskets.....and again your looking at #7 and #8 where 99% of the issue is located. The heads have a small water passage located at the rear of the block that is extremely close to the cylinder wall. Like about 1/8" or less. Because the aluminum heads and the cast iron block heat and cool at different rates (expansion and contraction of the metals) it wears the gaskets at this point. That is why when they brought out the LT1's on the C4's they reversed the coolant flow.

If your at all mechanical or have a friend that is, replacing the head gaskets is not that difficult. As noted above, have the heads checked by a good machine shop. Doing it yourself can save you a bundle of money and you will learn more about your car. If you go this direction....label every wire, hose, bracket, bolt....anything you remove....100% without exception. It will save you problems when your putting it back together.

cv67

Too many times, heads are pulled, a quickie valve job done and back together it goes.

Check your valve guides...maybe them and seals need to be replaced. That ought to take care of things.
A GM crate is cheap through Jegs or Summit.

drcook

what was done in 2010 and how many miles since then ?

if the oil burning started then, a valve seal(s) was(were) probably damaged during reassembly. do you have the parts list ? were new head bolts used or did they reuse the existing head bolts ? in which case there could be a sealing issue because of this

Joe C

this may have nothing with the problem at hand, but a little food for thought. it may have nothing to do with the head gasket, but the intake manifold gaskets. I saw this on a TV car show once. same situation - excessive oil consumption after a rebuild. drove them nuts trying to figure out the cause. did all normal testing things - nothing. the car was a 1961 or 62 corvette, and it seems the mating angles of the head and intake didn't quite match. i'm thinking the original rebuilder got something machined wrong, and the manifold gaskets would not seal, allowing oil to seep down into the intake ports. can't remember the exact details, but it seems to me, they got another intake, and problem solved. anyway, as I said, food for thought - good luck.

~ Anno Domini

Thank you guys, I'm reading all your comments and considering everything. Yes drcook the oil burning started right after the rebuld in 2010. I have the bill in front of me now. The guy who did the job has scribbly writing, so it's hard to read everything, but he lists cam bearings, rod and main bearings, pistons and rings, oil pump and screen, valve guides, engine gasket set, vitten seals, shims. The receipt says he re-used my cam and lifters because both appeared in good condition. Also says pressure test heads and overhaul heads. Machine shop labour to overhaul short block. Also says remove cylinder heads to pressure test and reface it, clean up valves, replace seals etc (he says "etc"), re + re short block to overhaul as required. The car was burning oil when I got it back and has been since 2010 (75000 km or 46,000 miles ago). I tried to get him to fix it, but it's a long story and he did not fix the oil burning and I have just lived with it ever since. I made some phone calls to local mechanics. They're talking about rebuilding the engine, but I can't afford that again. I would just like to fix the head gasket (stop the exhuast gases getting into the coolant) if possible and keep the car a few more years. Still praying on what to do. More later as I learn it.

~ Anno Domini

Question: Hypothetically speaking, IF the head gasket is leaking exhaust gasses into the coolant (with no coolant in the oil) is it possible to only change the head gasket to fix it ? I mean, just install a head gasket set like Fel-Pro Head Gasket Set HS7733PT-9 and nothing else and the car will run like it did before ? Also, do you ALWAYS have to machine/resurface the heads when changing a head gasket or can you manually use a ruler to see if it is straight that way ? Sorry for the simplistic questions, just wondering if this could work. Thank you.

jv9999

You want to make sure the gasket set is recommended for aluminum heads. IMO, you would likely be fine just replacing the gasket and even reusing the head bolts (they are not torque to yield). Of course if you want to have the lowest possible chance of not doing it again, it would be best to have the head checked and use new bolts. Are you feeling lucky? It's not a bad job in a C4 because access is so good. Other will disagree I'm sure :-)