preempting BHG?

[chris davey]

My mate is looking at an mx83 Cressida Grande. He said it looks very clean body wise and interior but I told him about the inherent BHG problem with 7m's. The owner has receipts for a whole heap of stuff including cam seals, main seals, timing belt etc. but no head gasket change. The car has 285000kms so from what I have heard of these engines I didn't think it was possible for it to last that long on the stock head gasket.

So is there any tests you can do to see if it could be on its way out. I told him to do a compression test and leak down but that will only test if it is already stuffed I would have thought.

So from BHG people, any signs to look for that it is on its way out?

Thanks

Chris

[takai]

If you have a look at the coolant and there is oil in it then that is a BHG, same in the opposite direction, i.e. coolant in the oil (makes it look like a chocolate milkshake).
They normally bust around cylinder 5 & 6 for some reason as well.

The best preventative is to start saving money, so that when it does go youll have enough to redo the HG properly. I.e. deck the block and head and put studs in with a better head gasket and more torque.

[Slim]

Take it for a good test drive... watch the temp guage, these things do NOT fluctuate AT ALL if they are in good working order. It can be 35 degrees outside and the temp needle will sit at the same level as it does on a 20 degree day. So if you see it getting hot at all then i'd start to worry about BHG.

Watch for white smoke (steam) out the exhaust on start up. If it's a bit slow to start that is sometimes related to a BHG (but obviously not always).

Oh, and for all your Cressida needs go take a look at www.thermactor.com/forum

[Stomps]

hey mate
another good way to check is to watch the overflow bottle, after a good drive if the overflow is full but the radiator is low then you could have BHG, if teh gasket is fine then it will create a seal and therefore a pressure difference allowing the water from the overflow to be sucked back in, if the gasket is blown or leeking there will be no pressure difference and water from the overflow will not be sucked back through..

but the best thing to do is save money and do the gasket anyway, depending on what the car is for maybe even go steel, for around $250 for a steel gasket it gives you peace of mind..

good luck
Stomps

[Slim]

I forgot to say that i agree with Takai that the best thing you can do is to just save up for when the gasket does go. It's often very hard to tell if it's on the verge or blowing.

Mine went 9 months after i bought the car which was also 9 months after the head gasket was done. Don't trust the workmanship of mechanics that you have never met. Just make sure that if the head gasket lets go at some point that you have a bit of cash in reserve to get the car back on the road.

It's a false economy to do a cheap head gasket job on these cars, they don't give you an inch. If it's not done exactly right it will blow again soon enough.

Having said all that i hope your friend still buys a Cressida... they're awesome cars, so well built, comfy and nice to drive. They're so cheap now too compared to when i bought mine. Good luck.

[RyleyMA61]

I drove my supra home from Adeliade to Ballarat and the temperature spiked once... I think this was when the BHG started to set in...

I can concur with what said here- my Supra had a metal headgasket installed by the previous owner and it blew 3 weeks after I bought it.

My symptoms were:
missing slightly at idle
Used coolant from overflow bottle
Creamy stuff on top of radiator cap
Temperature would rise at complete random events.

However:
The car still ran and boosted very well
No smoke, no water in oil and vise versa.

I've since replaced the headgasket with a stock item, reconditioned head, finished block, aftermarket head bolts, torqued correctly with appropriate wear-in periods before retorquing. (I can't recommend the new bolts and torquing enough)

When I got my supra back, I was allowed no boost for 500kms, then a retorque, then allowed a little bit of boost for 500kms, then a retorque, then good to go.

Good luck!

[rvrolla]

I dont recall reading the gurgling dash. It sounds like water trickling through the dash. This is due to exhaust gasses/air in the heater core.

While a MHG sounds like a simple solution, it is not always the case, if you are to do a MHG, you should really deck the block. A standard cork style HG will squash and contour to any imperfections on the head/block where a MHG wont as much. In my MZ20, I spent a mint of reconditioning the head and using HKS MHG ARP Studs etc and it still came back months later and bit me in the bum over heating, milky residue on oil cap etc cause I did not deck the block.
In my MX83, I had the head machined, used a standard cork HG (from VRS), new head bolts from toyota torqued down to 65 (i think it was ) I did this all myself and have not had a single problem yet, did it months ago. *runs off to touch some sort of wood!! *

[rvrolla]

Also, check http://thermactor.com/forum/

[jeffro ra28]

They normally bust around cylinder 5 & 6 for some reason as well.

Is the cooling intake on the front or back of the engine? im sure this would relate to it blowing in the end cylinders.

I am unfimaliar with this engine, where does the HG usually blow? the bridge between cylinders or cylinder-water jackets?

[rvrolla]

Between cylinder and water jackets usually. The cooling intake is at the front and the heater hose is right at the rear. Mine blew in Number six between water jacket and bore on both cars.

[chris davey]

Thanks guys.

I will let him know what you said.

He bought the car and unfortunately he said it is using a heap of petrol so I am thinking o2 sensor or coolant temp sensor possibly. Will do a diagnostics check tomorrow but if there is no errors I am not sure what to look for. I will do a search

[Slim]

lol... the 7mge is not known for its fuel economy. If by heaps you mean around 350km from a tank then i wouldn't bother looking for a fault other than the type of engine the car's fitted with.

If it's worse than that then the o2 sensor would be a good place to start looking. I know of a few people that had to replace them on Cressidas, me included.

[whatthe?]

Mine was similar to Ryleys but even milder, no creamy stuff in the oil cap, no missing at idle, it would just occasionally overheat randomly and blow coolant into the resevoir. A "Tee Kay" test (most mechanics have these) will tell you with almost 100% certainty if you have one as they use a fluid which changes colour if exhaust gases are detected in coolant. It was the only way that I could say with 100% certainty that my HG was blown

[takai]

About average for a MX83 is 400-450k per tank, whichi s around 60-65 litres.
As a few other people have said tell your mate to jump on Thermactor.com as that is the dedicated Cressida forums.

[chris davey]

Ok, thanks guys