Complete explaination could be lengthly so I'll try to hit the key points with short explanation.
Its a cruzer, not a racer. I may do a little stop sign burnout from time to time, can't help it.
87 vert. with Jasper 383 installed. 180 degree thermastat with chip installed. Approx. 35K on engine. No water leaks evident but looses water slowly (suspect out tail pipe), new cap anyway. Coolant temp. started running higher than normal when stopped at red light, 232 degrees. Temp OK on the road. New Radiator, checked it anyway - OK. Replaced coolant, Idled for a long time after burping, no problem. Went for a drive 30 or so miles, stopped at red light, temp. went up to 232 then came down when on the road????? Checked fans - OK. Water pump seems ok, feel surge when reving engine. Have not done a compression check yet, engine runs fine, changed plugs and all looked good. Let engine idle in drive way after running it to see how high it would go. 241 is as high as it went????

My theory. Some exhaust gasses cavitating pump when engine slowed to idle after running (heater in car does not blow hot air during this time but works normal when temp is normal?????) Suspect slight leak in head gasket. Oh, I do see vapor out the right side after everything is warmed up and shouldn't be any condensation in exhaust. Sorry so long, bout don't have any hair left. What do you think? Am I way offline.

There's a couple of ways you can check it. The easiest is to get a cooling system tester, pump it up to at least cap pressure, engine warm (t-stat open)and running. Observe the pressure gauge, it should be steady. If the needle is bouncing, it may be a head gasket. You may be able to tell which cyl by pulling plug wires one at a time and seeing if the gauge stops bouncing.

The other way is to do a leakdown test (better than a compression test anyway).
Doing a leak down takes more time and each cyl has to be at TDC (you need a compressor too).

I had temp spikes like this before. Turned out it was my thermostat sticking. Just a thought

another way to tell is look for a really clean spark plug , if you have a small head gasket leak it ill steam clean the plug

Yeah, I for some reason would not suspect a head gasket first. Unless you run it out of coolant or it gets really hot, I doubt its a gasket. I'd do some more testing and not jump the gun on a head removal.

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Forgot to mention I have changed that to. Oh and I did change the sending unit also. Both show the same temp readings. Pulled the belt off and spun the water pump. Didn't notice anything. Ever heard of a water pump going bad and not leaking? No water in oil and no oil in water.

Didn't think about the spark plug being steam cleaned. I have already trashed the old ones, Oh well. I may pull the new ones I just put in and see if there is a difference, thanks jonszr1.

I'm with ya biggrizzly about the more testing. Nothing points to the head gasket yet so before pulling the heads I need to make sure thats the problem. Thanks

Thanks BillH, it will be a part of my troubleshooting excersize. May take some time to find the actual cause. I think I may get my local mech. involved. He's pretty good. I'm just a shade tree.

Kinda aggrevating but it aint completly broke down yet. When the temp is elevated it seems like the water is not circulating. Thats got me stumpped. I want to find it and fix it before more damage is done. Thanks for the input.

On mine, when I ran it hard, it would push coolant into the overflow tank and overflow it. That was a bad head gasket for me, although they can have different symptoms than that.

The head gaskets on the L98 are suspect, at best.

Questions:

The 383 from Jasper; did you install your own heads in car?

If you answer "yes", then I suspect headgasket. You see, the bolts at #8 are hard to reach with a torque wrench, and even if the wrench clicks, it may not be applying the full torque to the bolts. #8 is prone to failure on the lower half, about 5-o'clock on the cylinder.

At this point, you either have a blown headgasket or, god forbid, a crack somewhere in the block or head.

Doing a compression or leakdown will confirm the gasket, may not confirm a crack.

Also, check the motor oil. If it has drops of water in it...

WHat about the L98 manifold gasket. It is prone to be a leaker in the back too. Correct?

You mention the L98 intake... the gasket can tear at the cooling journal and inject coolant into the engine.

Good point.

Hell, that is a very good point.

That problem won't show on a exhaust gass/coolant test.

I ended up having a hard to find leak at the gaskets for the water pump. I know another guy who had a hard to find leak at the oil cooler metal lines at the bracket.

If it's overheating like that, I'd burp it again. What technique are you using? Lift the front tires up, run the engine and use your hand to move the throttle body open until about 2000 rpm...when the coolant drops, add more then cap it off. Might have to do it twice.

I'd try the pressure test and there is also a test for exhaust gasses in the coolant.

Matthew

I will throw this in one more time. Check the thermostat.

last couple of time my temps spiked, it was the fan motor going out.

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Didn't think about that. Fan spins when cool but heat may change rpms of the fan motor. Question, will the amps be higher when everything is warmed up? How did you know the fan motor was going bad? Mine still runs but didn't notice the difference in RPMs.

Bogus - Jasper mounted heads
Matatk - Burped it on ramps but worth doing it again before pulling heads.
Steve40th - Its a new thermostat but I won't rule that out either. Ran car in driveway with term. open and have good flow in rad.

I'm going to do the pressure checks and compression test and see what that shows. Thanks guys for the input, really.

I believe if the fan is spinning fast, it is good.

Make sure the primary fan is working and coming on at the right temp (I'd guess on at 200 and off at 185 for a 180 thermostat). The aux. fan (in front of the radiator) will turn on around 230. It is set by a separate coolant temp sensor in the driver's side head, therefore the chip will not change when it turns on.

Since you said you can see the flow in the radiator when the thermostat opens I would guess the water pump and thermostat are doing their job. It sounds alot to me like fans not coming on as early as they should, or a bunch of garbage and leaves between the radiator and condenser (when did you last clean that cavity out?), or even a radiator hose sucking shut (unlikely since the temp is ok while driving down the road but still worth looking at).

Also you said you see vapor out the right side of the exhaust. Do you have true dual exhaust? If you still have a Y pipe and single resonator then there is no way that antifreeze vapor would be coming out one side and not the other. It would have to be condensation in a muffler or something.

I wouldn't go pulling heads just yet, this just seems like a fan or radiator issue to me.

Pull the valve covers see if there is condensation in them.

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Stop theorizing and guessing. Just get a Block Tester with Liquid Test Dye and you'll know within 5 minutes if the coolant portion of your head gaskets are really blown or not. You can find these for purchase or rental at certain parts stores. It's highly accurate, and it's easier and faster than any of the methods given above for testing this part of the head gasket.

Autozone has this one that works great:

The Block Tester is $25

OEM Part# 27145





The Test Dye is $8

OEM Part# 25739



How to use one:

http://www.youtube.com/watch?v=QA7KVQq9vKA

Mr. 86PACER, the test you advised proved my theory. I found some antifreeze in the back of the engine by #7 cylinder. Then I went and got the tester at Auto Zone and yep, pee yellow it turned. Looks like I've got some work to do but will wait until it gets a little warmer. Yes I will have the heads checked when the work is done. Thanks guys for all the input. I knew I could count on ya'll. Luv this site.

Update;

Finally got around to doing the work. Pulled the heads and yep, just as I suspected. Found a very small channel in the head and gasket in the #7 cylinder. This channel lined up center of the small water jacket hole in the head where exhaust gasses could get into the cooling system.

Took the heads to a machine shop and they found both heads were warped. No cracks and had resurfacing done. They didn't find anything else wrong with them. I did notice those head bolts on that corner of the engice were easier to break loose than the rest.

I'll start putting the engine back together in about a week and a half (since I'm working now and won't be off till then). Its been suggested to go back with ARP bolts so they are ordered. Also ordered the gaskets recommended by Jasper. New water pump, plugs, wires, cap, rotor, hoses and exhaust bolts (anybody had any problem getting the old ones out of the manifold?). Got a lot of cleaning to do before installation begins.

Just thought someone may be interested in the outcome since this was a puzzle to me finding the problem. If I were to have another engine built I think I would use a local builder than buy one built on an assembly line. Jasper is good to do bussiness with but I think maybe too many hands were in the pot during the build. I found the rocker arm nuts tighter on the right bank than on the left bank so that makes me wonder if the heads were torqued by the same individual. No rant, just an observation.

Glad you got it figured out.

Thank you for updating the post.

Thanks for the update!

What exhaust bolts are you referring to? I would soak any bolts overnight with some pb blaster if you are concerned. Since you have a week until you do this, shoot them a couple times before hand and you'll be all set.

Matthew

Yea, I didn't say which ones but its the exhaust manifold bolts to connect the flange. I soaked them in Marvel Mystry oil before heading to work and will dose them more while cleaning everything. Hope that works. They've been there 24 yrs thats why I'm concerned. If soaking don't work I guess I'll have to break out the torch and heatm a little. Thanks.

Glad you found it, but the leak is classic L98. Sorry to say.

Be ready to do those exhause bolts some justice.

I had the weld on the flange break off! I ended up welding the flange back on and then drilled them out and used a nut bolt arrangement.

Heads shaved, bolts and sealing surfaces cleaned, threads tapped, parts received, ready for assembly. I was thinking, why not remove all that crap associated with the AIR pump and gut the pump. It would be easy to cut and krimp the tubing to the exhaust manifolds while off. Looking for opinions, WWYD? It sure would clean up the engine compartment considerably. Also going to bypass the water flow from the throttle body. Anyone had any adverse affects from doing any of this?

Easier than crimping the tubing is just putting a pipe cap on the threaded end. Some guys have cut the tubing flush and welding the hole shut.

No drawback to the TB bypass unless you plan on running your car in 0 degree weather quite often.

Matthew

Update; Fired her up at 3:50 pm. Purs like a kitten now. Did the AIR delete and gutted the pump. Engine compartment cleaned up nicely. Best mod (except the 383 stroker) I've done. Bearings were nasty on the rear of the pump. I cleaned them and packed with grease. Should last awhile. I do feel a little pride in accomplishing this as well as saving a bundle of $$$$. Thanks again to all who gave input. You helped me more than you know. Ya'll have a good day and God bless!

I just remembered something about the tune. The computer adjusts for the air pump being there and pumping air (when on) to the 02 sensor. It is a very minor adjustment, but can affect the a/f mix. So it's good to mention it to your tuner. Check with Mick for more specifics.

Matthew

Thanks Matt. No codes yet but haven't ran it much. Its a different prom than OEM since I put the 383 in. Will drive it for a while and check milage to see if anything has changed. Milage I expect to go up a little. AIR sytem may not have been programmed in, not sure thou.

I did notice the starter struggling a little, not sure if it is from the increased compression ratio or the starter going bad. I still have the OEM starter in there now. Jaspers paperwork said the ratio is 9.7/1. With the heads shaved, my mech said it'l probly go up approx. 2-3/100. If I'm not to badly mistaken, the OEM motor is 9.1/1. That is a considerable difference. Anyway, one thing at a time. I'll address the needs as they occur. Thanks again.
Rex

Your starter should handle the additional compression without a problem. In later models the compression bumped up closer to 9.5:1. My 383 is 10.5:1 with the stocker rebuilt. More than likely it's just showing age and possibly heat related failure due to headers, etc.

Matthew

Bought a new starter anyway. Got the Powermaster 9100. Wasn't the starter after all. Battery is 4 yrs old. It was to weak to crank over a warm engine. Don't regret getting the mini. I luv it.