'97 Q45 enigne overheated and overflowed coolant resevoir.

[97Q45t]

My '97 Q45 started to have the sign of slow warm-up and the coolant level in the resevoir raised slowly each time when I checked it for about 5-6 months before. A couple days ago, the engine began to show sign of overheating (temp gauge moved up a little bit). Yesterday, the engine overheated and the reservoir got fill-up with a much faster rate, especially at highway speed.

From my understanding, the cylinder head gaskets are bad so the exhaust gas leaked into the cooling system and caused the eigne to overheat. Is there any other cause beside the head gasket failure before I try to replace them? How long does the job take? Do I need to take the engine out like the FSM said? Thanks!

[qship96]

i think you should have a pro diagnose the problem,hopefully it is not the headgasket{has 2, but doubtful both would fail at the same time.} many times leaky headgaskets allow coolant into the combustion chambers which could result in a very expensive rebiuld or engine replacement.

[maxnix]

I would say unlikely unless you saw a ton of white smoke issuing from the tailpipes. In any case, don't run it if you think coolant is entering combustion chamber as acids are readily formed that destroy aluminum.

Remove radiator and thermostat and examine water pump. Time to rehab the cooling system.

[97Q45t]

Also when I cleaned the coolant resevoir yesterday I saw lots of white flakes (like sugar coated flakes on donuts) on the walls of the revevoir. There was light white smoke at start-up on cold mornings but no smoke at all on hot/warm days or when the engine is warmed-up.

[sijoko]

You should have a good shop, maybe the dealer, do a leak-down test. This will tell you if the head gasket is blown.

If it turns out the head gasket is gone, then it might be cheaper to just pick up a used engine.

I saw one eBay a few weeks ago for less than $800 (VH41DE).

-sijoko

[maxnix]

You should have a good shop, maybe the dealer, do a leak-down test. This will tell you if the head gasket is blown.

Well, not necessarily as a valve could be faulty. But you should definitely see if the engine is holding compression. Never hear of head gaskets failing on these engines, though.

[elwesso]

Well, not necessarily as a valve could be faulty. But you should definitely see if the engine is holding compression. Never hear of head gaskets failing on these engines, though.

I agree, but how would a valve make any difference??

On the caddy forums, where this is common, a guy had the same thing happen. The fluid would spew out the overflow tank (on the caddys its pressurised with the rest of the system)... No smoke, didnt even overheat, but would just spew coolant everywhere.....

Id get the leakdown test done and see whats happening..... How does the oil look, any goofy looking oil?

[DAEDALUS]

The HG can be a victim of an overheat, as happened to tkd_q45, but is likely not the root cause of the problem, as Maxnix said.

The pressure test suggested by Sijoko is one method of determining a bad HG, but sometimes doesn't work if the leak only happens at operating temp or under combustion pressures. 600psi vs 15psi! Another method is a kit you can buy that will detect the presence of combustion gases in the cooling system. Oil in coolant and/or coolant in the oil are near-certain clues.Certainty is a must before contemplating such a repair. It's a real beauty, I'd be heartbroken for ya if the HG is bad.

[elwesso]

It's a real beauty, I'd be heartbroken for ya if the HG is bad.

Yeah, esp on your Q. Why cant it be on some neglected Q that deserves it...

Good excuse to do a VH45 Swap

[maxnix]

Good excuse to do a VH45 Swap

Besides being a federal violation, the only OBD IIVH45DE engine is the 1996. Probably not an inexpensive swap.

[97Q45t]

... How does the oil look, any goofy looking oil?

Oil looks fine. Coolant looks fine. I'll bring my car to the shop tomorrow for a diagnosis.

A VH45DE swap sounds intersting! I could then supercharge it with the kit you're developing.

[3Q Jay]

ouch, Duy. first thing I would try is the cardboard fan clutch test, and then the thermostat.

[97Q45t]

Jay, I took the thermostat off a few days ago. Obviously the engine was still overheated. What is a cardboard fan clutch test?

[FarFetched]

I am sorry to hear that man! I would check W/P (slow warm ups), (overflow reservoir getting full).Best bet to check HG is to break out a "SNIFFER" just like other fellas sugested to see if combustion gases enter cooling system. Aluminum engines don't like to run hot or heads warpage may occure!Damn it, such a nice, clean Q45 and illnes has taken over! Cardboard test is - where you try to stop fan blades - that's as far as I know If you got exessive play in your fan clutch (side-to-side) it is no good, it could have lost "silicone" and just spinning free w/o getting "locked up" when needed!

[97Q45t]

I got the car back from the shop yesterday. They said that it is more likely that the radiator is clogged. Since I put a new radiator last summer, I took the [Koyo] radiator off today for an exchange (lifetime warranty). New radiator will be here tomorrow. I hope the overheating problem will go away.

[DAEDALUS]

That's great news! Hopefully it didn't run too hot before you figured it out. Keep 'er shining.

EDIT: What clogged the radiator?

[97Q45t]

What clogged the radiator?

I think the white stuff (flakes), like sugar coating on donuts. Last year I ran my car with 100% tap water for 1-2 days while replacing/fixing the radiator. When new radiator was in, I put 50% coolant, 50% tap water until the problem arised recently. Could the tap water be the cause to all of this? I used the 50/50 premix coolant now.

[maxnix]

In Houston, yes. ALWAYS use only distilled water when contacting aluminum alloy.

[FarFetched]

Let me pitch in on this matter. I have an extensive fleet experience with coolants/additives. First, since GM has come out with "silica" based coolants, life of cooling systems became a bit easier. "Silica" compound creates less tension in coolant. Although it may show a weakness of your system, in general switching to "long life coolant is a VERY GOOD idea!Second, to maintain proper coolant (all coolant have either propylene or ethylene glycol base) you need to maintain proper additive pakage ecxept "long life" coolants. It is very important as "bad" coolant will eat away aluminum. I have seen it trust me. Three factors that play an important role in service life of a coolant mix are PH, Freeze Point, and Nitrate. Ph - is your acidity level (eats away materials), Freeze point -is obviously ability to stay liquid. Nitrate level is critical to maintain proper electrolysis and to contain errosion. "silica" based coolants don't have 2 of three components, just simply freese point. So there is a clear advantage of "long life" coolant over a convetional 50/50 mix "the green shizer" Fleetguard is on the few companies that really understans cooling system needs. http://www.fleetguard.com/fleet/en/index.jspDo a good flush before you switch to a "long Life" coolant, check for leaks (weaknesses of cooling system), enjoy longer service intervals Cheers!

[97Q45t]

VERDICT: Clogged radiator caused the engine to overheat. New radiator was in, car runs fine now . Thanks to all who replied!

[Jesda]

Did you go OEM or aftermarket? Metal end tanks?

[maxnix]

Glad to hear it! Be sure to use distilled water only and consider converting to OAT coolant.

[97Q45t]

Jesda, the radiator I got has plastic ends. It was Koyo, exactly like stock one but without the Nissan logo. Made in Indonesia. Quality is about a 9/10 of a stock. At $160 with lifetime warranty, I can't complain.

Brian, I used premixed coolant this time. What is OAT coolant?

[3Q Jay]

Duy, OAT= Organic Acid Technology. It's the prestone 'Orange' stuff sometimes marketed as 'dexcool'. could be other trade names too, dunno.

echo Brian on distilled H20 only-also you will want 12 oz of water wetter.

My mix on all my cars is 30% OAT, 12 oz WW, rest distilled H20.